iRhythm Technologies, Inc. Common Stock (IRTC) Q4 2021 Earnings Call Transcript

iRhythm Technologies, Inc. Common Stock (IRTC -1.88%)
Q4 2021 Earnings Call
Feb 23, 2022, 4:30 p.m. ET

Contents:

• Prepared Remarks
• Questions and Answers
• Call Participants

Prepared Remarks:

Operator

Good day, and thank you for standing by. Welcome to the iRhythm Technologies, Inc. fourth quarter 2021 earnings conference call. At this time, all participants are in a listen-only mode.

After the speakers' presentation, there will be a question-and-answer session. [Operator instructions] Please be advised that today's conference is being recorded. [Operator instructions] I would now like to hand the conference over to your speaker today, Leigh Salvo. Please go ahead.

Leigh Salvo -- Investor Relations

Thank you all for participating in today's call. Earlier today, iRhythm released financial results for the fourth quarter ended December 31, 2021. A copy of the press release is available on the company's website. Before we begin, I'd like to remind you that management will make statements during this call that include forward-looking statements within the meaning of the federal securities laws, which are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.

Any statements contained in this call that are not statements of historical fact should be deemed to be forward-looking statements. All forward-looking statements are based upon our current estimates and various assumptions. The factors that could cause actual results to differ materially from those expressed or implied by any of these forward-looking statements are detailed in iRhythm's Annual Report on Form 10-K, most recently quarterly report on Form 10-Q, and other filings with the Securities and Exchange Commission. Except as required by law, we assume no obligation to update any such forward-looking statements after the date of this presentation or to conform to these forward-looking statements to actual results.

In addition, we will discuss certain financial measures that have not been prepared in accordance with GAAP with respect to our non-GAAP and cash-based results. Unless otherwise noted, all references to financial metrics are presented on a non-GAAP basis. The presentation of this additional information should not be considered in isolation or as a substitute for results or superior to results prepared in accordance with GAAP. Please refer to the tables in our earnings release for a reconciliation of these measures to the most directly comparable GAAP financial measure.

For a list and description of the risks and uncertainties associated with our business, please refer to the risk factors section of our most recent Annual Report and quarterly reports on Form 10-K and Form 10-Q, respectively, with the SEC. This conference call contains time-sensitive information and is accurate only as of the live broadcast today, February 23, 2022. iRhythm disclaims any intention or obligation except as required by law to update or revise any financial projections or forward-looking statements, whether because of new information, future events or otherwise. And with that, I'll turn the call over to Quentin Blackford, iRhythm's president and CEO. 

Quentin Blackford -- President and Chief Executive Officer

Thank you, Leigh. Good afternoon, and thank you all for joining us. Doug Devine, our COO and CFO; and Dan Wilson, our EVP of corporate strategy and investor relations, are joining me on today's call. My prepared remarks today cover progress we've made since our last call and commentary on the near and long-term growth initiatives we are focused on for our business.

I'll then turn the call to Doug to provide a detailed review of our Q4 and full year 2021 results, as well as guidance for 2022. It's been an exciting four months since I joined iRhythm, and I could not be prouder or more energized by our team's collective progress. In this short time, we have identified and begun to implement measures that we are confident will enable us to accelerate growth in our core market and expand our opportunity into adjacent ones. We have also begun to implement operational changes that we believe will generate long-term sustainable growth and enable iRhythm to scale even more efficiently.

I recently shared reflections from my first 100 days with the iRhythm family, and I'd like to share some of that with you today. My vision is to turn iRhythm into a truly global organization, expanding the value we've realized domestically and extending across the world. Our artificial intelligence capability and deep learning algorithms are a significant differentiator from competitors, lifting our value well beyond medical devices and into the future of what AI can deliver. We see opportunities to leverage our core technology for new use cases not considered five years ago that can deliver significant value for both the healthcare system and our investors while keeping iRhythm at the forefront of revolutionizing the way healthcare operates.

Good progress has been made, but our work is far from done. The potential is tremendous, and our focus remains on delivering value to our clinicians, payors, and patients. We have a global responsibility to get these technologies out there more broadly and to get more people access to care. With that in mind, we are focused on three primary growth pillars.

First, continued expansion in our core market with Zio XT and Zio AT. As the leader in this space, we recently reached an exciting milestone of surpassing 4 million patients served. Today, physicians are treating well above 1 million new patients each year with our best-in-class technology that leverages more than a billion hours of curated ECG data and truly delivers the gold standard in ambulatory cardiac monitoring. We still have plenty of runway ahead of us with less than 25% adoption in our core U.S.

market, as well as an opportunity to further expand this market in time. Second, expansion into international markets. We have made great progress in operationalizing our service in the United Kingdom and plan to submit for Shonin approval in Japan later this year. Beyond these two countries, we see immense potential to introduce our technology platform in international markets and to make Zio the standard of care in cardiac monitoring, similar to the successes we've seen in the U.S.

And third, leveraging our technology platform to expand into adjacent markets. Our efforts here are led by our expansion strategy in the silent AF, which is extending our Zio XT service into asymptomatic and high-risk patient populations that can potentially benefit from proactive monitoring. We also see the potential to leverage our technology platform into adjacent disorder and disease categories. With that as a backdrop, I'll summarize our 2021 and fourth quarter performance, trends we're seeing in the early part of 2022, and recent progress on the objectives I've just outlined.

For the full year 2021, our revenue grew 22% over 2020, exceeding the guidance we offered on our last call. Fourth quarter revenue reflected year-over-year growth of 3.8% and nearly 20% unit volume growth against an unseasonably strong fourth quarter in 2020. Adjusting for approximately one week of clinical backlog in Q2 that rolled into our third quarter, Q4 sequential growth was approximately 8%. And importantly, our turnaround times in clinical queue remained with an expected balance throughout the quarter.

We saw a nice rebound in new account openings in the fourth quarter as we restarted targeted efforts after successfully addressing our midyear turnaround time issues. We were also encouraged to see average volume per new account near an all-time high since we began tracking this metric at the end of 2017, which signaled the ability to launch larger accounts and ramp new accounts more quickly. New accounts typically ramp up over a four-quarter period following launch, which suggests more meaningful contributions from these new account launches in the back half of 2022. Throughout much of the fourth quarter, our business recovered well from the combination of the clinical backlog and COVID disruption.

In late December, the omicron variant spike had a meaningful impact on our business that continued through January. We have seen stronger trends in February and recently surpassed all-time record daily registrations. While we are encouraged by the recent trends and the strength of our commercial pipeline, we do anticipate continuing staffing and labor shortage headwinds combined with the impact of fewer new account launches in both the second quarter and third quarter of 2021 will have an impact in the first half of this year. Diving deeper into our core market in the U.S.

and starting with Zio XT, unit growth continued to outpace revenue growth as a result of the reimbursement headwind that we navigated throughout 2021. Encouragingly, our sales reps have started to gain traction expanding beyond cardiologists and EP call points to reach primary care physicians where an estimated 8 million people a year visit for heart palpitations. As I have highlighted previously, we expect this to be an important driver of near-term growth in our core market while also expanding our addressable market in time. On the innovation front, we recently launched ZioSuite 3.0, which includes single sign-on, as well as multifactor authentication.

These features will be rolled out to all of our U.S. customers over the next 90 days and represent the outstanding cross-functional efforts we hope to build upon in our core technology offering. We plan to continue bringing new technologies to market, including a limited introduction of our third-generation biosensor expected in the coming months. Lastly, on the reimbursement front, we were pleased with the progress in Medicare pricing in early January with the decision by Novitas to update their 2022 reimbursement rates that affect Zio XT, moving rates from the seven to 14-day code from $115 in 2021 to $233 in 2022.

We appreciate the continued engagement and efforts of the MACs to better understand long-term continuous ECG monitoring, the clinical benefits that it provides to patients, and the cost and resources that go into delivering the service. The updated rates demonstrate progress in further understanding costs associated with delivering the Zio service. We, along with a broad industrywide working group, will continue to work with the MACs, the Centers for Medicare and Medicaid Services, or CMS, and other stakeholders to provide information in support of our continued pursuit of fair and appropriate pricing. We are committed to providing as much information as we can to CMS to allow them to set a national rate for calendar year 2023.

We believe that they have sufficient information to establish national pricing, and we look forward to the proposed rule in July or August of this year. On Zio AT, we saw strong growth throughout 2021 that outpaced overall company growth. Revenues from Zio AT doubled in 2021 versus 2020 and now represent approximately 10% of our revenues. We are pleased with the ramp of Zio AT and see an opportunity to continue to grow the product.

Clinical use cases, including TAVR, syncope, and early discharge have been key drivers for Zio AT, and we are evaluating several other opportunities to expand the use cases and the value that we can deliver to patients and physicians through clinical evidence and continued innovation. Now turning to International, we continue to make good traction in both the private and public sectors in the U.K. where roughly 500,000 ambulatory cardiac monitoring tests take place each year. The backing and support of the NHS grant and the AI award, as well as the NICE recommendation, gives us confidence that the U.K.

can be a significant market for us in the future. Our focus remains on executing against the AI award to demonstrate the clinical and economic value of our Zio XT service and generate the data required to achieve long-term sustainable reimbursement in the U.K. The success we are seeing in the U.K. combined with CE Mark approval already in hand gives us the added confidence to pursue other markets throughout the EU, where we can deploy resources and begin growing our presence.

We have also accelerated our efforts into Japan where we are moving forward with an application for regulatory approval. Japan is the second largest ambulatory cardiac monitoring market in the world, where reimbursement has historically been very good and physicians have been expressing strong interest in our technology. To oversee the execution of our international expansion goals, we are delighted to welcome Sandrine Moirez as our new international general manager. Prior to joining us, Sandrine spent more than 20 years with Medtronic, most recently leading EMEA commercial efforts including sales and marketing for spine, biologics, and several other key divisions.

Turning to our third pillar of growth and the one that I believe has the most significant long-term potential are the adjacent markets. Our initial efforts are focused on silent AFib, where we estimate there are more than 10 million people in the U.S. alone that are at high risk of undiagnosed cardiac arrhythmias who can benefit from early screening. Additionally, there are other adjacencies like predictive stroke, heart failure, hypertension or sleep apnea that can contribute to an enormous addressable market opportunity in the future.

These are areas that we believe our technology platform can be leveraged to address clear unmet needs, and we look forward to sharing more details as we initiate efforts in these areas. In addition to our focus on growth, we are committed to improving operational discipline that will lead to long-term profitability and meaningful financial leverage over time. We are rethinking how we conduct our business in evaluating longer-term operating models that can enable future efficiencies and scale with the business as we globalize our company. Internally, we have begun to prioritize efforts with respect to our algorithms that will automate workflows for our clinical operations teams.

We're evaluating the utilization of software to enhance interactions with our customer service functions. We've launched formal efforts to review our operational processes across our back office, transactional functions to clearly map out opportunities for efficiencies and new ways of doing business into the future. And we're doing this while also committed to improving upon our overall control environment as we introduce world-class operational capabilities. In line with these efforts, we will incur some restructuring charges within the first quarter of 2022 that are primarily associated with the reduction in size of our San Francisco facility to better align the company to be a remote working environment that we have proven to be successful.

With pricing near existing levels and with these operational changes underway, I am confident that we have adequate capital and a clear path to positive EBITDA and positive cash flows without the need for diluted financing to get us to profitability. In summary, I'm confident that we have entered 2022 with good momentum and a platform to grow and serve millions more patients. We are intently focused on this vision, and we look forward to sharing our progress throughout the year. I will now turn the call over to Doug.

Doug Devine -- Chief Operating Officer and Chief Financial Officer

Thanks, Quentin. Our fourth quarter results reflected the resilience of our teams through a highly uncertain environment. Having resolved our clinical operations backlog in the third quarter, the fourth quarter saw registrations and new account onboarding return to growth, which has set the company up for further revenue growth in 2022. Taking a more detailed look at our fourth quarter financial results on a sequential basis, revenue declined 4.2% due to the one-time benefit in Q3 from reducing clinical backlog by about one week, not reoccurring in the fourth quarter, offset by growth in volumes from new accounts.

Growth in our average daily registrations was solid, increasing by about 7% during the fourth quarter as compared to the third quarter. New account onboarding increased both in the number of new accounts opened and the volume from new accounts with volume from new accounts more than doubling as compared to the third quarter of 2021. Looking at new store/same store mix, new store, defined as accounts that have been open for less than 12 months, accounted for 46% of year-over-year unit growth, up from 29% in the third quarter of 2021. XT Home enrollment was up slightly to approximately 21% in the fourth quarter.

Home enrollment has continued to decline to approximately 22% so far in the first quarter of 2022. Turning our attention to the rest of the P&L, gross margin for the fourth quarter was 62.7%, a 3% decrease compared to gross margin of 65.7% in Q3 of 2021. The decrease was due to lower sales volumes, higher shipping rates, and higher staffing costs in both our manufacturing and clinical operations organizations as we staff those functions ahead of anticipated revenue growth in 2022. Operating expenses for the fourth quarter were $83.5 million, up 5% from Q3 of 2021 and up 23% year over year.

The sequential increase in operating expense was the result of a milestone expense to Verily of $3 million and an increase in bad debt expense. Verily costs included in opex were $3 million in Q4 '21 compared to $4 million in Q4 '20. The company expects the next Verily milestone to occur in 2023. Adjusted EBITDA of negative $17.3 million in Q4 '21 was down $8.6 million versus Q3 '21 adjusted EBITDA of negative $8.7 million.

Cash and short-term investments declined $17.7 million from the third quarter of 2021 to $239.1 million. Adjusted EBITDA losses, repayment of long-term debt, and capital spending were the primary uses of cash, partially offset by improvements in working capital. Accounts receivable decreased by $6.4 million to $46.4 million from $52.8 million in Q3 2021 as we continued to make progress with payors on adjudicating claims that were held in the first half of 2021. Finally, net loss was negative $32.4 million or a loss of $1.10 per share compared with a net loss of $9.7 million or $0.33 per share in the same period of the prior year.

Turning to guidance for 2022, we expect full year revenue to range between $400 million and $410 million, reflecting year-over-year growth of 24% to 27%. We expect gross margin to range between 67% and 68%. This reflects Novitas' updated reimbursement rates retroactive to January 1, 2022. Had these pricing changes been in effect for 2021, it would have increased our 2021 revenue by approximately 10%.

We expect operating expenses to range between $375 million and $385 million. We expect adjusted EBITDA to range between negative $30 million and negative $40 million. Our adjusted EBITDA for 2022 will exclude restructuring costs that Quentin noted earlier and will continue to exclude stock compensation expense. Due to omicron impact to patient registration volume in December and January, we expect Q1 revenue to be a bit below typical seasonality, which was approximately 22% of full year revenue in the first quarter of years prior to the COVID-19 pandemic.

We expect to see gross margins steadily improve throughout the year and close the year around 70%. The first quarter of 2022 will also see some higher COVID expenses to gross margin due to staffing and testing impacts. Finally, we have signed a term sheet with Silicon Valley Bank to restructure our existing debt facility. The new facility will be nondilutive, extend the maturity, reduce the cost of capital, and increase the amount of capital available by two to three times our current facility.

We expect to close the facility by quarter end and will provide further details when appropriate. And with that, Quentin, Dan, and I would like to now open the call for questions. Operator? 

Questions & Answers:

Operator

[Operator instructions] Please stand by while we compile the Q&A roster. Our first question comes from the line of Allen Gong from J.P. Morgan. Your line is now open.

Allen Gong -- J.P. Morgan -- Analyst

Hey, guys, congratulations on the good quarter. I guess my first question is going to be on reimbursement. It was really great to see you guys get the higher rates kind of under your belt so early on in the year. But when we think about the national pricing, should we think of you as feeling confident that you can get at least that rate, if not better? How have your kind of communications with CMS gone so far and what gives you the confidence to move so quickly on national pricing?

Quentin Blackford -- President and Chief Executive Officer

Allen, thanks for the question. Look, I think we're very encouraged with the pace of the discussions and the content of the discussions that continue to take place with CMS. We're in the middle of those as we speak. We continue to educate them.

I think really encouraging was the fact that they wanted to be made aware of the information that we shared with the MACs that was pulled together by the third-party compilers of the financial data across the entire industry. And for them to want to get into those details and see what was behind that was really interesting to us because we know they have a bit of a different approach historically to how they go about pricing this, but they continue to demonstrate their desire to want to learn as much as they can around the cost profile and the value that's delivered here. I see that as a very encouraging sign. And my sense is also that CMS and the MACs are communicating throughout this process, which I'm not sure has always been the case historically.

We've always had our discussions certainly with the MACs, and those continue, and we've had them with CMS, but it seems that those two parties seem to be communicating as well, which I see as an encouraging sign. I'm not going to try to speculate on where they go with the rate. I feel very good about the fact that they have all the information they need at this point to make a decision. They have a lot of information in front of them that certainly would articulate a higher price point than what's been established with the MACs, and we absolutely believe that the value we deliver is far beyond that rate as well.

I'm excited by where this is moving. But again, I'm not going to speculate on where it goes, but I am encouraged by what I'm seeing.

Allen Gong -- J.P. Morgan -- Analyst

Got it. And then just a quick little follow-on. When I look at your guidance range, it certainly brackets kind of where consensus was going into the print. But just from your point of view, what really gets you to the bottom versus the top of that range? And with some uncertainty around the trajectory of the pandemic, whether or not we might see another seasonal impact in the fall or winter, or if there might even be another variant on the way, what does your guidance contemplate for those kinds of factors? Thank you very much. 

Quentin Blackford -- President and Chief Executive Officer

Yeah. We try to anticipate, to the greatest degree possible, those sort of headwinds in our guidance. We can't foretell what the future is going to bring in the back half of the year, but I can tell you I feel like we've become much better as an organization learning how to navigate through these potential challenges as they're created. We have tools like home enrollment that we've seen step up over the last several weeks and into the new year that continue to demonstrate it's a viable model that can help us navigate these sorts of headwinds.

We try to do our best to forecast those. I will tell you, when you get into the last part of December and in the early part of January, there's no question omicron had an impact on the business, but we navigated it fairly well. And if you look at the last several weeks of February here, it's encouraging to see numerous daily record registration numbers coming through. And really, if you look at the last three to four weeks, every week has stepped up sequentially off of that, so the momentum is building.

We're very excited by what we're seeing there. But at the same time, we want to be thoughtful when we set guidance expectations to anticipate a bit of what could be out there. And to the degree that we can navigate through that well, then I think we're going to be very happy with the result at the end of the year. But I think the company is getting better at navigating through those sorts of things. 

Operator

Thank you. Our next question comes from the line of Cecilia Furlong from Morgan Stanley. Your line is now open.

Unknown speaker -- Morgan Stanley -- Analyst

Hey, thank you for taking the question. It's Calvin on for Cecilia. Congrats on strong quarter. Just a couple of quick ones for me.

The first one is, I wanted to start on the margin guide. It sounds like it's primarily baking in the Novitas update pricing. I'm just curious, on the AT side, it looks like the '22 PFS showed kind of a 20%+ increase in the MCT rate. I was hoping you could walk us through how much potential benefit on pricing, on margin and on volume ramp of AT drives as you look at '22 and potentially beyond? 

Quentin Blackford -- President and Chief Executive Officer

Yeah, I'll take that out of the gate. And Doug, you certainly can feel free to chime in there in terms of specific impacts on margins, although I don't know that we've given that level of detail in the past around particular product profiles on the margin. Certainly, we were encouraged by what we saw with the increased rate around the Zio AT product with Noridian in particular. I think it continues to demonstrate that the value of the product is being realized by the MACs.

We don't miss the opportunity when we sit down with them to articulate what our product can deliver into the marketplace, and to see that get reflected in updated rates is encouraging. And from our perspective, with respect to margins, those are the sort of things that we generally let flow through. And so there certainly has been a benefit from the AT movement on the rate, although it's not a significant part of our business just yet. I wouldn't say that it's moving margin profiles in a significant manner, but it is something that we let flow through.

Doug, I don't know if there's anything you want to add to that in particular, but feel free. 

Doug Devine -- Chief Operating Officer and Chief Financial Officer

Just as you're familiar with, Calvin, AT is currently about 10% of our revenue. And you're looking at roughly half of AT is impacted by that Medicare price increase. It's not an impact on the commercial. So that gives you a feel.

It's incrementally positive. It's not a significant needle mover at the company level on gross margin.

Unknown speaker -- Morgan Stanley -- Analyst

Got it. Thanks. Just two really quick follow-ups. The first one is, could you talk a little bit about your business organization optimization kind of goals specifically around how you're thinking about your goals on Salesforce augmentation as you brought in your kind of physician reach and bring more kind of PCPs under the tent, how much of that would occur in '22 versus beyond if you're thinking about augmenting the organization? And then secondly, just on clinical trial kind of readouts or data readouts for the remainder of this year on GUARD AF and the mSToPS cost-effectiveness data, are those still on track for '22? Thanks so much. 

Quentin Blackford -- President and Chief Executive Officer

Sure. So let me hit the augmentation question around Salesforce first in particular, primary care. The interesting thing that you find in our business to date is that our most successful reps have found ways to navigate into that primary care channel already with some reps seeing up to 20% or more of their book of business coming through the primary care space, which I think validates 100% that there's an opportunity to move into that space, and we need to find ways to focus more on that more broadly across the commercial force. But part of that is also freeing up that commercial force to be able to call on those primary care physicians.

And we've looked at various models. Our guidance anticipates some incremental investments this year around the commercial force with respect to supplementing them with different profiles of sales reps, if you will, or associate reps, we call them key account managers that can free up the territory managers to go in and look for new business say in that primary care space. And it does that in a much more cost-efficient way. We are looking at all angles of how we can free up our folks to be more effective and call on more new accounts with the primary care physician, a primary target of that.

I think as we think about the future and just how large that primary care space is, we're putting all sorts of opportunities on the table that we're evaluating right now from looking at increasing our own commercial force, do you potentially partner with others to move into that primary care space? Can you approach it through a payor perspective or through an IDN or a GPO perspective and have it kind of come top down into the PCP space? Those are all things that we're evaluating at this point in time, and I think you should expect to hear more about that in the latter part of the year as we really fine-tune that strategy and execute on that more broadly. With respect to the clinical trials, GUARD-AF continues to move. Obviously, that's not our own sponsored study. That's coming from Pfizer and Bristol.

But from everything we can tell there, it's moving in a very favorable manner, and we would expect to hear some readouts here in the not-too-distant future is kind of how we're expecting or anticipating to see things come from that. And we are continuing to move down the path of pulling together the economic components of the mSToPS study that demonstrate the value financially speaking of the ability to screen more proactively and engage earlier with these sorts of AFib situations. And so I'm encouraged by what we're seeing there. I would expect you'll see something in the latter part of the year around that.

Unknown speaker -- Morgan Stanley -- Analyst

Great, thank you.

Operator

Thank you. Our next question comes from the line of Margaret Kaczor from William Blair. Your line is now open.

Maggie Boeye -- William Blair -- Analyst

Hey, guys. This is Maggie Boeye on for Margaret today. I wanted to kind of hit on what you're assuming for pricing benefits and underlying growth for 2022. Our initial read on the model suggests a mid- to high 20% growth rate on sales growth, which implies a deceleration of unit growth.

Does this mean that there is conservatism baked in, or is there something else you should keep in mind here? Thanks. 

Quentin Blackford -- President and Chief Executive Officer

Yeah, great question, and thank you for it. The way we approached guidance was -- and this is an approach you'll find that we'll take into the future, we want to be very thoughtful around the way that we set expectations. We want to expect or anticipate what those headwinds are. And then we've put plans in place to navigate through those and execute well against them.

And to the degree that we do, then I think we'll all be very happy with the outcome, and we expect there to be upside to the expectations that we set. If those headwinds come to fruition, then they're not negative surprises. That's sort of how we think about guidance. We set our guidance for 2022 from a volume perspective with expectations of nearly 20% on the volume growth side.

And then obviously, you get about 10% benefit coming from the Medicare rate change offset by low single-digit pricing pressure in the rest of the business that we've consistently seen over the last several years, so a pretty consistent approach to what we've seen. Your note on the slow growth profile, I would just point you back to the fact that that '21 unit growth profile comes off of a 2020 number that was impacted by COVID in a pretty significant way. And I think if you readjusted that '21 growth for a more normalized 2020, unit growth was probably somewhere around 25% in 2021. Which on an absolute unit number is pretty comparable to the way that we're guiding 2022.

I don't think you're seeing any changes in the trends of the business. We feel very good around the overall momentum in the business, and we've tried to be very thoughtful around the headwinds. And like I said, to the degree we navigate them well, I think we're all going to feel very good about the year. 

Maggie Boeye -- William Blair -- Analyst

Got it. Thank you. You mentioned earlier on the call that during Q2 and Q3 of '21, you pulled back on new account openings. Can you talk about, as we head into 2022, how you're back on the offensive in new accounts? And can you give us some color on how long these new accounts could take to ramp up and really start contributing to sales? Thanks so much. 

Quentin Blackford -- President and Chief Executive Officer

Yeah, you heard a little bit of this in our prepared remarks. We were very encouraged with the way that we saw the new account activity sort of begin to really take hold in the fourth quarter coming off of two quarters of where we had really pulled back new account openings. In the fourth quarter, we saw a nice step-up in the number of new accounts we're doing business with. But importantly, near a record high in terms of the average unit volume per new accounts.

It was the second highest quarter on record for us since we ever began measuring that metric dating all the way back into 2017. We were very encouraged with the pace of which new accounts were coming on, but also the size of the new accounts that were coming on, which I think really speaks to the field team's ability to target those high-profile accounts and then win those accounts and bring them into the iRhythm family. We were encouraged by that. I think that you come into January, you continue to see the benefits coming from the new accounts.

Certainly, we had the omicron impact in the early part of January, but we've navigated through it pretty well to where we're back to record daily levels of registrations continuing to build in February. I think we've navigated through the near-term impacts. Those new accounts generally take about four quarters to really come up to speed if you will, and they step up on a pro rata basis kind of on a quarter-by-quarter basis. But by the time they get to the four quarters of having done business with us, they're usually at a pretty stable run rate and have grown into their potential.

I think what that does is sets us up in the back half of the year for some nice incremental growth coming from some of these record levels of new accounts or size of new accounts that give us confidence on the year.

Maggie Boeye -- William Blair -- Analyst

Great, thank you.

Operator

Thank you. Our next question comes from the line of David Rescott from Truist. Your line is now open.

David Rescott -- Truist Securities -- Analyst

Hey, guys, thanks for taking the questions, and congrats on the strong end to the year. I guess first one, just on the guidance, I appreciate the commentary you provided around some of the moving pieces there. It seems like kind of this plus 20% growth rate in Zio XT. You mentioned just some comments on the ASP impact there as well.

But how should we think about the AT and International segments impacting growth in 2022? I know that you mentioned there was obviously an ASP increase to AT. That business doubled in 2022. How should we think about that this year? And then what does guidance contemplate as far as when new products come into the international expansion or the international markets? 

Doug Devine -- Chief Operating Officer and Chief Financial Officer

Yeah. Those guidance figures that I provided, David, our overall company guidance figures, Zio XT and Zio AT combined, obviously, AT is embedded in that. We do continue to believe it will grow at a faster rate than the XT business. We haven't given specific color on how fast we expect it to grow.

But when I think about the opportunity there, we probably have nearly 25% of the ACM market utilizing Zio XT, maybe no more than 7% or so of market share in the Zio AT opportunity. There's tremendous runway and we continue to focus on positioning that product in a way that can get after it. I do think there are some things we need to do on the product side to continue to make it even more competitive in that space. But I think when you look at it, the value of what you can get off of 14 days in that MCT space versus a traditional 30-day monitor, it's superior with our product even in the less number of days that they're sensing for.

We've got to continue to educate and create awareness around that potential. On the international side, I think of international, not as a significant driver of growth just yet. Obviously, the only place we're doing any meaningful business there right now is in the U.K., and that's still in a hyper-growth mode, but we're working through the scenario right now where we're trying to get put in place permanent reimbursement long term. We're still working underneath that AI award in that country.

Now we have started to target the private sector as well, which will bring with it some nice growth. But I think it's more of a let's wait and see how that plays out versus get out ahead of ourselves with respect to those expectations. I think longer term, international is going to be a meaningful contributor to overall growth for the company. But the reality is most of that is going to be a market access effort opening up opportunities over the course of this year and revenue probably doesn't really start to come from those efforts until the back half of 2023 most likely as we start to target new additional countries that we're going to take the product into.

I think for the year, international is going to be -- not going to be a huge driver of growth, but there will be a tremendous amount of opportunity going on there that sets it up for being a nice driver of growth into the future. 

David Rescott -- Truist Securities -- Analyst

OK. That's helpful. I guess just to clarify, the 20% plus growth rate is total blended growth for volumes, not specifically to Zio XT?

Doug Devine -- Chief Operating Officer and Chief Financial Officer

That's right.

David Rescott -- Truist Securities -- Analyst

OK. I guess just on the commercial front, I know you've always talked about in the past how there is the thought that commercial payors may ultimately adjust their rates based on what the NCD rate comes out to be. If we think about a rate in 2023 from NCD regardless of where that rate is or direction of where that rate goes, do you think the commercial payors at this point would shift their rates toward a national coverage decision, whether it's one and a half or 1.25 times that of CMS? Or do you think that commercial payors at this point likely have determined the rates at which they would continue to maintain on a go-forward basis and just after there is an NCD? 

Quentin Blackford -- President and Chief Executive Officer

Yeah. My view is, generally speaking, the commercial payers understand the value of this product. And they've consistently looked at this product differently than what CMS or the MACs had done historically. Now I do think CMS and the MACs are coming around to understand it differently than what they had historically, and you hear that now in those conversations with those parties where they will describe the Zio product for example as being very different than traditional Holter monitors.

We know that CMS and the MACs have come around to look at this a little bit differently. And I think the commercial payors have always sort of taken the position from the very beginning that they see us differently. And that's why you didn't see them make any drastic reaction to the CMS or the MAC rates in the past. They were clear that they thought that CMS and the MACs would come around to see this in a different light, and I think that's what we've seen.

I believe commercial payors, again, they understand the value for what it is. I don't see a lot of significant concerns around getting a national rate locked in and then seeing pressure on the commercial business. That's just not the way the majority of those discussions are going. Are there a couple of commercial payors here there who might peg their rate directly to the CMS? There are, but those are not significant volumes and significant payors for the most part.

And I feel like we've navigated that very well historically. The other thing that I think is interesting, and we'll spend more time talking about this into the future, but I'm not sure there's the difference between the commercial rate and the CMS rate that maybe most folks anticipate there might be. We've done a pretty good job I think of negotiating into a place where there's not the sort of risk that our investor profile might believe that sits out there. But we'll spend more time around that in the future as we provide more clarity into the business.

David Rescott -- Truist Securities -- Analyst

OK, very helpful. Thanks for taking my questions.

Operator

Thank you. Our next question comes from the line of David Saxon from Needham. Your line is now open.

David Saxon -- Needham and Company -- Analyst

Good afternoon and thanks for taking the questions. Maybe one on national pricing. Quentin, in the script you mentioned that you think CMS has enough information to establish national pricing. So just wondering, since the $200 price that they came out with late last year was just an average of 10 invoices, I guess are you aware of any additional invoices that have been submitted that could change that average price? Or are they relying upon those 10 invoices or perhaps are they changing their approach altogether?

Quentin Blackford -- President and Chief Executive Officer

Yeah. I don't know that they're changing their approach. As I shared, they've been interested in going through the cost model that was presented to the MACs by the third party that consolidated that information. I know that discussion has happened, but I don't know that they're changing their approach.

I don't have any information that would indicate they're going to change their approach. I think it's just more corroborative of the sort of place that they may be landing at. And again, I'm not going to speculate where that is, but it's encouraging to me that they're wanting to get all of this information together and learn as much as they can. I have to believe there's more information being submitted to them as we speak.

We're certainly doing our part to engage with them and continue to articulate the value of our product, and I'm sure every other player around the industry who has a vested interest is probably doing the same thing. But I'm not going to speak on their behalf or on behalf of CMS, but I would expect that more information is coming into them. 

David Saxon -- Needham and Company -- Analyst

OK. That's helpful. And then I guess just with regards to the Silent AF opportunity, you talked in the past about wanting to start these pilots. Just wondering, would they look something similar to what you did with Aetna and mSToPS? Or would they just be designed differently? And then if I could just sneak a third one in, you mentioned getting into sleep apnea and predictive stroke, etc.

Any preliminary timelines you could share and whether that would leverage the Zio Patch or watch or would be a different form factor? Thanks so much for taking the questions and congrats on the quarter.

Quentin Blackford -- President and Chief Executive Officer

Sure. I'll ask Dan to step in and speak to silent AF and some of the pilot work that's being done there. He's done a terrific job leading this effort with him and his team, and I'll let him speak to that. 

Dan Wilson -- Executive Vice President of Strategy, Corporate Development and Investor Relations

Yeah. Thanks for the question, David. First, we're really pleased with the progress. As Quentin mentioned, we have a great team behind this effort and we're making a lot of good progress in the market.

Your question about what does it look like, you're essentially right, it's essentially mSToPS and commercializing that type of program. We've built a minimally viable product so to speak that extends our capabilities beyond just the monitoring to the elements of patient identification, patient engagement on the frontend, and then diagnosing and communicating with the patient on the backend. We're building out those capabilities and really pleased with the progress there, and we are in the market actively selling those programs and hope to have a lot of positive updates to share as we go through the year. 

Quentin Blackford -- President and Chief Executive Officer

And just to close that out then on the whole comment around predictive stroke, predictive heart failure, sleep apnea, those sorts of adjacencies, those are all, in my mind, real potential opportunities for this company and others. There's work to be done around it, and there are things that we're doing inside the organization right now to elevate the focus around these sorts of things and make them larger priorities for us. But it's a bit too early to speak to exactly what that looks like. But when you get into the dataset that we have, more than 4 billion hours of curated heartbeat data, I think it's amazing what we're going to be able to find when we start to really dig through that data and put these sorts of opportunities in front of the AI capability that the company has built.

It's just a matter of focus. We'll speak more to it in the future, but it is something you're going to hear us talk more and more about as I believe five-plus years into the future, the adjacent market opportunities are going to be something we're all spending a lot of time talking about and realizing the benefit of.

David Saxon -- Needham and Company -- Analyst

Great. Thanks so much.

Operator

Thank you. [Operator instructions] Our next question comes from the line of Suraj Kalia from Oppenheimer and Company. Your line is now open.

Suraj Kalia -- Oppenheimer and Company -- Analyst

Perfect. Congrats on the quarter. Quentin, a couple of questions at least from my side. As expected, you have started talking about operational changes for long-term profitability.

That's a welcome sign. The question I have, Quentin, and please forgive me if I misunderstood this, the AI that you talked about on the backend, does that imply some multilayer technician review is going to be obsoleted over time? And if so, how do you manage type two errors that are inherent in any algorithm?

Quentin Blackford -- President and Chief Executive Officer

Yes. Suraj, thanks for the question. I don't -- I'm not trying to indicate any real changes in that clinical oversight. I think there's a lot of work we can do with the algorithms in terms of how we collate the data, how we group the data, and who and how much time we spend with it.

It's clear that some reports come in with more issues associated with them that need to be dug into further, and other reports are more clean. The better we can do at grouping those sorts of reports and making it more efficient for our technicians to work through those, the more effective and efficient that we can become over time. I do think when you look at the capability of our AI capability, it's very clear, and we've shown this back through the Nature publication a year or so ago, that we can identify and diagnose AFib equivalent to expert personnel, expert physicians. And we've only improved that algorithm since we've introduced it, which means we start to move beyond that.

And so, I do think the AI capability that we have here is truly unique in that it's leveraging 34 layers of deep neural network that I don't think our competition can speak to. I think there is highly differentiated capability there. But in terms of how it reduces oversight of the physician, we're not speaking that that's the case. It's more about how it groups the reports and how we look at it in terms of driving efficiencies in the organization.

Suraj Kalia -- Oppenheimer and Company -- Analyst

Got it. Quentin, one for you and one for Doug, if I may, and I'll drop back in queue. Quentin, you mentioned adjacent diseases such as heart palpitations and stroke, and whatnot. I guess in sleep apnea, Quentin, I'll just pick on one, sleep apnea.

ResMed did a pretty big study in the yesteryears, with sleep apnea and AFib correlation. It failed. And the question I have is, what is it, to the extent that you can talk about it now, you all are going to be doing differently that hasn't been done so far? How do you get paid for it? And Doug, if I could just throw in quickly, what is the run rate at which you'll expect iRhythm to become profitable with all the operationalized changes that you are implementing obviously a few years down the line? Gentlemen, thank you for taking my questions, and congrats again. 

Quentin Blackford -- President and Chief Executive Officer

Thanks for the questions, Suraj. Look, I think with sleep apnea, there's still a lot to be learned in that particular space. We know there's 25 million-plus patients in the U.S. who are impacted by this.

Exactly what the reimbursement model would look like I think is work yet to be done. What I do know and believe to be the potential is that as we continue to move further into that primary care space, you start to afford yourself the opportunity to look for more and more things and sense more and more capabilities. And sleep apnea is one of those things that we think would be very appealing to be monitoring for identifying in that PCP space. We understand the challenges of getting into the sleep clinics today, the backlogs that are associated with it, how ineffective it can be, and the need for repeat visits back into those.

I believe there's a real opportunity to sort of change the way diagnosis of sleep apnea is thought about. And I believe with the right attention, resources, work, and effort behind it, there's some interesting things we can do off of the patch that make it a realistic possibility and potential for us. And so, as we get up into those upstream channels, I think we afford the ability to start to look for more things, sleep apnea is one of those things that's interesting to us. But exactly how it comes together, those are all things that we continue to have to work through and navigate through and reimbursement is one of them.

With that, Doug, I'll turn it to you.

Doug Devine -- Chief Operating Officer and Chief Financial Officer

Yeah. Thanks, Quentin. So Suraj, I mean, first, when you look at our guidance for this year and revenue is going to be increasing as we go through the year and gross margin is going to be increasing throughout the year, so we are going to be seeing leverage. You should be expecting that we'll be at least around breakeven EBITDA in Q4 this year with these levels of pricing if not a slightly positive EBITDA in the fourth quarter or adjusted quarter of this year.

And obviously, we're not going to talk big volume run rate where we get to a positive other than my comments on Q4 other than to say that it is of course dependent on where the final level of Medicare pricing ends up landing. 

Operator

Thank you. Our next question comes from the line of Bill Plovanic from Canaccord. Your line is now open.

Bill Plovanic -- Canaccord Genuity -- Analyst

Great. Thanks for taking my question. A couple of kind of housekeeping questions here. First is just, Doug, on the Zio AT, I think your commentary was that it was about 10% of revenue.

Was that for the fourth quarter or for all of 2021? 

Doug Devine -- Chief Operating Officer and Chief Financial Officer

It's been running about that run rate through Q2, Q3, and Q4. It was a little bit below on the first quarter. 

Bill Plovanic -- Canaccord Genuity -- Analyst

OK. And then secondly, I think your commentary had something also on an increase in bad debt for the fourth quarter. Is that due to the delayed kind of submissions back in early in the year? And is this something that we should expect to kind of hit into the fourth quarter or into 2022? Or is that pretty much all being cleaned up with this? 

Doug Devine -- Chief Operating Officer and Chief Financial Officer

No. We had actually seen one-time good news on bad debt in Q3. And so Q4 bad debt was just returning to the normal expected levels. 

Bill Plovanic -- Canaccord Genuity -- Analyst

OK. And then lastly, and this may have been covered, but as you commercialize, you talk about the asymptomatic space, and I know there were some questions on this, but has it been determined if you're going with the Verily wearable or with the iRhythm Zio watch? Have you made a decision on which one you're going to go to market with? Or will it be two separate products going to the market? I apologize if that question has already been asked.

Quentin Blackford -- President and Chief Executive Officer

No, no issues, Bill. That question had not been asked, but our initial efforts are to go to market with the patch, with our ZIO Patch. We're not going to wait for the watch itself. We'll launch some pilots here in the not-too-distant future that will utilize the patch technology that we already have.

And then with a better form factor in the future, we'll drop that into these programs as they get going. We're not going to hold up and wait around. We're very bullish on the opportunity here. I think it's incredibly clear through the mSToPS data in particular just how valuable it is to get out there and start to monitor these broader populations, and we know we can do that with the existing patch form factor.

We're not going to wait on that.

Bill Plovanic -- Canaccord Genuity -- Analyst

Great. That's all I have. Thanks for taking my questions.

Quentin Blackford -- President and Chief Executive Officer

Thanks, Bill.

Operator

Thank you. At this time, I'm showing no further questions. I would like to turn the call back over to Quentin Blackford for closing remarks. 

Quentin Blackford -- President and Chief Executive Officer

Well, thank you all for your time this evening. As I close, I want to thank each and every one of our incredible iRhythm employees. 2021 was a year that presented the opportunity for many distractions over the course of the year, yet the team was steadfast in their efforts to help as many people as possible, and we once again saw record numbers of new patients and their lives changed as a result of our best-in-class technology. This would not have been possible without the wonderful people who are here.

With that, we appreciate your interest in iRhythm, and we look forward to speaking with you all again soon.

Operator

[Operator signoff]

Duration: 55 minutes

Call participants:

Leigh Salvo -- Investor Relations

Quentin Blackford -- President and Chief Executive Officer

Doug Devine -- Chief Operating Officer and Chief Financial Officer

Allen Gong -- J.P. Morgan -- Analyst

Unknown speaker -- Morgan Stanley -- Analyst

Maggie Boeye -- William Blair -- Analyst

David Rescott -- Truist Securities -- Analyst

David Saxon -- Needham and Company -- Analyst

Dan Wilson -- Executive Vice President of Strategy, Corporate Development and Investor Relations

Suraj Kalia -- Oppenheimer and Company -- Analyst

Bill Plovanic -- Canaccord Genuity -- Analyst

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