Hello and welcome to the iRhythm Technologies, Inc. Q1 2024 Earnings Conference Call. My name is Terry, and I will be your operator today. I would now like to turn it over to Stephanie Zhadkevich, Director of Investor Relations, to begin. Please proceed.

Thank you all for participating in today's call. Earlier today, iRhythm released financial results for the first quarter ended March 31, 2024. 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 federal securities laws 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 facts should be deemed to be forward-looking statements. These are based upon our current estimates and various assumptions and reflect management's intentions, beliefs, and expectations about future events, strategies, competition, products, and operating plans and performance. These statements involve risks and uncertainties that could cause actual results or events to materially differ from those anticipated or implied by these forward-looking statements. Accordingly, you should not place undue reliance on these statements. 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 and quarterly reports on Form 10-K and Form 10-Q, respectively, filed with the Securities and Exchange Commission. Also during the call, we will discuss certain financial measures that have not been prepared in accordance with U.S. GAAP with respect to our non-GAAP and cash-based results, including adjusted EBITDA, adjusted operating expenses, and adjusted net loss. Unless otherwise noted, all references to financial metrics are presented on a non-GAAP basis. The presentation of additional information should not be considered in isolation as a substitute for or superior to results prepared in accordance with GAAP. Please refer to the tables in our earnings release and 10-Q for a reconciliation of these measures to the most directly comparable GAAP financial measures. Unless otherwise noted, all references to financial measures in this call other than revenue refer to non-GAAP results. This conference call contains time-sensitive information and is accurate only as of the live broadcast today, May 2, 2024. 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.

Thank you, Stephanie. Good afternoon, and thank you all for joining us. Brice Bobzien, our Chief Financial Officer; and Dan Wilson, our EVP of Corporate Development and Investor Relations, are joining me on today's call. My prepared remarks today cover business updates during the first quarter of 2024 as well as our annual outlook. I'll then turn the call over to Brice to provide a detailed review of our first quarter financial results and updated 2024 guidance. During the first quarter of 2024, we achieved revenue of $131.9 million, representing 18.4% growth compared to the first quarter of 2023. Over 0.5 million registrations in Q1 contributed to another quarter of record revenue volume, while our average selling prices remained steady with the prior year. Drivers of growth continued to come from the focus of our land and expand strategy by going deeper and broader within existing accounts, as well as a meaningful contribution from new account openings. The first quarter was again a strong quarter of new account onboarding as we matched our highest ever quarter for new account openings for Zio long-term continuous monitoring, reflective of our team's ability to capitalize on our pipeline opportunities and providing confidence in our 2024 outlook. Our teams drove solid momentum during the first quarter as we have seen strong market demand for our Zio products and services thus far in Q2 as well. These factors have resulted in our updating of annual revenue guidance, reflecting our ongoing confidence in the underlying fundamentals of the core business and optimism for continued market capture in 2024. Our excitement for the primary care channel continues to grow as our two-pronged approach to opening that opportunity gains traction. As a reminder, we are approaching this opportunity by working from the ground up within large health networks that our current cardiologists and electrophysiologists are part of today, while also targeting the large national innovative primary care providers. During the quarter, we were pleased to have entered into additional partnerships with several innovative national primary care networks, further demonstrating these groups' growing appreciation for Zio's ease of use, high patient compliance, and ability to deliver clinical accuracy while reducing the cost of care. Importantly, we have seen the continued uptick in utilization from these early national primary care adopters over the course of the quarter and are excited about their potential throughout the year and into 2025. Important to our growth, we have seen continued traction from within large integrated multidisciplinary care networks where Zio's value proposition as a workflow efficiency tool is clearly resonating, as these networks push prescribing further up the care pathway into the primary care channel. Out of all accounts ordering the Zio Services in 2023, almost half had at least one primary care prescriber in their care network. But perhaps more importantly, volume growth in 2023 from cardiologists was higher in those accounts that were part of multidisciplinary care networks and that had at least one primary care prescriber compared to accounts that do not have a primary care prescriber in their network. This diversification into different specialties is not only a driving factor and further penetration within these networks, but it is also a validation that primary care is an important partner to alleviate backlogs associated with capacity-constrained workflows. This has already played out at several representative IDNs where we have seen primary care participation and we believe that we are only getting started to expand patient access to Zio and many more of these opportunities to continue driving this workflow efficiency for our customers and enable even more streamlined access to Zio for our patients in the future. We were very excited to have recently announced a collaboration with Epic Aura, becoming the first medical device manufacturer to join the Epic community to use Aura. This collaboration will expand access to our Zio services across the continuum of patient care within health care systems from cardiology to primary care to hospital to home and beyond, and should help systems simplify operations while optimizing clinician workflows. Through this partnership, iRhythm and Epic will enable health systems to implement Zio services more efficiently, and we estimate that institutions can save up to 75% of the time it typically takes to integrate Zio services into local instances of Epic. The initial inbound interest from accounts wanting to leverage the iRhythm Epic partnership has been terrific and we have already started to partner with early adopters to integrate Zio Services into the Aura network across their health systems. As we advance this effort, we expect to begin offering this solution to both existing and new Zio customers starting in early 2025. Further contributing to our record success has been traction in large innovative care networks, where Zio has become the ambulatory cardiac monitor of choice for monitoring programs within asymptomatic patient populations. With mSToPS economic analysis published showing the benefits of identifying patients who are at risk for undiagnosed arrhythmias before their symptoms become severe, proactive screening programs using Zio services are gaining traction within innovative primary care groups, home health groups, and accountable care organizations. These accounts are highly focused on preventative care and value-added patient wellness programs for their members, and they have been very receptive to our strong clinical evidence demonstrating that monitoring for up to 14 days with Zio long-term continuous monitoring service maximizes diagnostic yield compared to monitoring with Holter for 24 to 48 hours. This means that Zio monitor services have the potential to provide the right answer the first time for those patients and better inform the care pathways for those individuals, potentially reducing downstream clinical events and the future cost of care associated with those clinical events and possibly addressing the growing capacity challenges within the health networks we serve. As a fantastic example of this, recall that we began to pilot our Know Your Rhythm program with our partner, Physician Care Centers, or PCC, for clinicians to proactively screen patients to identify those that meet the mSToPS inclusion criteria and are believed to be at risk of undiagnosed arrhythmias to determine if they would benefit from Zio monitor services. This program was primarily designed to identify patients that may be at risk for experiencing asymptomatic A-fib by implementing proactive screening guidelines according to the mSToPS exclusion criteria. Of the initial asymptomatic patients that were ordered the Zio monitor services in this pilot, 80% of these patients had at least one arrhythmia identified. Since there is a three times greater risk of developing heart failure and a five times greater risk of stroke if A-fib is a comorbidity, we believe that early identification of A-fib is crucial to develop clinical intervention strategies and reduce downstream adverse events. We are excited that this initial pilot is now transitioning into commercial launch, and we look forward to providing additional updates around this movement into the asymptomatic population as we move throughout the year. In our international business, we continue to move forward with our expansion efforts into multiple European countries as well as Japan. During the first quarter, our teams drove strong registration growth in the U.K. with volumes above forecast through expansion within the private sector hospitals. These sites have recognized the value of Zio Services as having a positive impact on patient waiting times, hospital resource utilization, clinical diagnostic yield, and pathway cost savings. In parallel, we continue to advance efforts to argue for an enhanced long-term reimbursement rate in the U.K. Additionally, now that we have received CE marking under EU MDR for Zio monitor and our ZEUS system, we kicked off a market evaluation in two Spanish hospitals in March and continue to anticipate the commercial launch of the Zio monitor services in the Netherlands, Spain, Switzerland, and Austria in the back half of 2024. In Europe as well as Japan, we believe there remains significant unmet clinical need for improved arrhythmia detection as the prevalence of arrhythmias and stroke continues to rise with the predominant monitoring technology still being Holter monitors. In our Zio AT business, recall that we submitted two 510(k) files in January, one is a catch-up for changes previously made to the Zio AT system as a letter to file and a second 510(k) for design features and labeling updates to further address areas of focus noted in the FDA warning letter. Since these submissions early in the quarter in support of Zio AT, we've been in dialogue with the FDA and continue to believe that we could receive a clearance decision from the FDA on our submissions in the second half of 2024. In parallel, our teams continue to work diligently to prepare for the subsequent filing for our next-generation MCT product, Zio MCT, and we believe that 510(k) submission for that product will be submitted late in the second half of 2024. As these near and midterm opportunities are being further fostered within traditional cardiac monitoring, we have also begun to explore possibilities beyond pure arrhythmia monitoring and into natural adjacent markets. As mentioned, this past February, we launched a sleep pilot program with approximately five to ten existing iRhythm customers intended to validate the value of streamlining the current journey of getting to a sleep diagnosis for both physicians and patients. We intend to utilize our call point and establish customer relationships with a combination of cardiologists and primary care physicians to validate the potential commercial opportunity and physician desire to streamline the prescription of home sleep tests and diagnose sleep disorders with a focus on obstructive sleep apnea. The goal of this pilot is to determine if cardiologists and PCPs will prescribe a home sleep test, collect metrics such as to which patients these physicians may prescribe a home sleep test, and determine how iRhythm can best be positioned to contribute to improved care for patients with obstructive sleep apnea, including through the delivery of this service through an integrated digital platform that will provide us a differentiated ability to address what we believe have been long-term challenges in this space. We have been encouraged by the interest thus far in this initiative, especially with the rapid onboarding of customer accounts for this pilot just beginning to launch. The early forays into adjacent markets are being further supported by scientific evidence. Our teams and academic partners are generating in support of EKG as a critical vital sign for predictive clinical insights. As a recent example from ACC last month, study findings from our collaboration with Duke Health concluded that incorporating EKG data from long-term continuous monitoring with the CHAD VAS score has greater discrimination than the existing clinical scoring system alone for the risk of heart failure hospitalization and new onset heart failure. Furthermore, authors concluded that the risk scores developed via this new model were able to more accurately predict Medicare cost in both treated and untreated patients. These conclusions are the starting point to develop risk models that include long-term EKG data, such as that provided by Zio products and services to inform diagnosis and management of high-risk patients while also being used by health systems and payers to develop interventions to reduce health care utilization and costs. As multiple vital signs and digital data assets are increasingly combined to generate these types of clinical insights, we are uniquely positioned for success far into the future. With that, I'll now turn the call over to Brice to discuss our recent financial performance.

Thanks, Quentin. As a reminder, unless otherwise noted, the financial metrics that I discuss today will be presented on a non-GAAP basis. Reconciliations to GAAP can be found in today's earnings release and on our IR website. First quarter 2024 results demonstrated positive momentum in our core markets as we achieved revenue of $131.9 million, representing 18.4% year-over-year growth. As Quentin mentioned, this was driven by strong revenue volume growth as well as a slight improvement to our average selling price of approximately 100 basis points year-over-year. New store growth with new store defined as accounts that have been opened for less than 12 months accounted for approximately 46% of our year-over-year volume growth. Consistent with recent trends, home enrollment for Zio Services was approximately 21% of volume in the first quarter. Gross margin for the first quarter was 66.3%, in line with expectations and with the guidance provided in February. As previously discussed, we have continued to see positive marketplace reaction to Zio monitor, and we are focused on managing the incremental costs associated with ramping capacity. We remain on track to realize the benefits of automation and scale for Zio monitor production in the second half of 2024. Additionally, since completing the last phase of our San Francisco IDTF investment in the fourth quarter, we are ramping utilization from newly hired clinical cardiac technicians as planned, and we expect to see continued improvements in efficiency as they come up to speed. First quarter adjusted operating expenses were $125.7 million, up 10% sequentially and up 15% year-over-year, in line with our expectations. Compared to the first quarter of 2023, this increase in adjusted operating expenses was primarily due to incremental resources to support volume growth in our operations. Sequentially, expenses were elevated due to seasonal items such as our global sales and leadership meetings, as well as annual compensation-related items. We continue to incur incremental legal and consulting fees as well as other company expenses related to the FDA warning letter and DOJ subpoena, and these are in line with the guidance previously provided. Revenue growth outpaced increases in operating expenses, showing our ability to drive sustainable operating leverage throughout the P&L. Adjusted net loss in the first quarter was approximately $38.1 million, or a loss of $1.23 per share compared to an adjusted net loss of $33.4 million, or an adjusted net loss of $1.10 per share in the first quarter of 2023. Adjusted EBITDA in the first quarter of 2024 was minus $12.1 million, reflecting minus 9.2% of revenue compared to minus 10.8% in the first quarter of 2023. We continue to make progress in our adjusted EBITDA margin profile, driving a 160 basis point improvement in adjusted EBITDA as a percentage of revenue year-over-year in the face of the temporal pressure on gross margin associated with the Zio monitor launch and the San Francisco IDTF investment. Turning to guidance, we are updating our 2024 outlook as presented earlier this year and now anticipate full year revenue of approximately $578 million to $588 million. We believe that the year will be driven by sustained volume growth in our core U.S. market as we continue to drive penetration in both existing and new customer accounts. With strong momentum exiting the first quarter, we believe that our second quarter 2024 revenue will be in line with the historical seasonality of approximately 25% of full year revenues. Turning to gross margin, we're reiterating our full year 2024 gross margin guidance in a range of 68% to 69%, an improvement of approximately 120 basis points at midpoint compared to the full year of 2023. Our outlook on phasing throughout the year remains unchanged, with material improvement manifesting in the back half of the year. We expect efficiencies to be driven by the majority of our business being transitioned to the Zio monitor platform, the ramp of automation lines to produce Zio monitor, and our clinical operations team in San Francisco operating at full capacity. For 2024, we are also reiterating our adjusted EBITDA margin guidance to range between 3% to 4% of revenues, which would represent a 400 to 500 basis point improvement compared to 2023, in line with our stated path to adjusted EBITDA margin targets in 2027 and driven by our focus on sustainable operating leverage improvements throughout the P&L. Adjusted EBITDA excludes impairment and restructuring costs, business transformation costs, stock-based compensation expenses, and the loss incurred in the first quarter associated with the early extinguishment of our debt with Silicon Valley Bank and Bradwell. Looking at the cadence of margin expansion throughout 2024, we expect to see second quarter adjusted EBITDA margin to be around breakeven with progressive margin expansion in the back half of the year. Along with anticipated progress in gross margin efficiency, operating expenses are historically more elevated than the first half of the year relative to revenue. As mentioned last quarter, we continue to believe that there will be approximately $8 million to $10 million of cost predominantly incurred in the first half of 2024, associated with the FDA warning letter and responses to the DOJ subpoena. As we navigate these two issues, the majority of these costs will come out of the P&L in the future. Finally, we ended the first quarter in a strong financial position with approximately $569.1 million in unrestricted cash and short-term investments, inclusive of financing activities and uses of cash for operations and capital investments. As disclosed in March, we further bolstered our balance sheet with cost-efficient capital through the closing of $661.25 million of convertible senior notes at a 1.5% coupon interest rate. As we have demonstrated, we will continuously evaluate our capital structure to ensure financial flexibility and alignment with shareholder interests. With that, I'd like to turn it back to Quentin before we open it up to questions.

Thanks, Brice. We are incredibly pleased with the start of the year and couldn't be more excited about the future in front of us. iRhythm is building a digital healthcare portfolio of the future. We are uniquely positioned for success as we continue to build our technology platform and leverage our commercial reach, established market position, patient-centric technology focus, expansive EKG data repository, and robust evidence generation strategy, which puts us in a position to be a market leader in defining how patient monitoring can look in the future as we address the Quintuple Aim of healthcare in the years to come. With that, Brice, Dan, and I would like to now open the call for questions. Operator?

The first question on the line comes from Allen Gong of JPMorgan.

Congratulations on a great quarter. I just have one quick one to start. In the first quarter, you called out how you had a little bit of a challenge in January with some weather-related impacts, strong February. And it looks like that momentum kind of continued into March. So just kind of curious to hear if you're still seeing that strong momentum from, say, Zio Monitor and AT so far into the second quarter?

Allen, it's Quentin here. We have continued to see that momentum continue into the second quarter to date. And to your point, we really saw that momentum begin to pick up in the back part of Q1. And I would say it's been unchanged, relatively speaking here in the first part of the second quarter through the month of April. So it has continued, and we've seen it continue on both the monitor product line as well as the AT product line.

The next question on the line comes from Malgorzata Kaczor of William Blair.

I guess I'd like to spend a little time around some of the data and time saving that you guys referenced around Epic Aura, 75% sounds pretty meaningful. So I'm just curious how meaningful is that to the user, if you can conceptualize it? And kind of the follow-up to that is I imagine those time savings were classed as step 1. But ultimately, that should lead to share taking or market expansion. So I guess, when should we start to get a better sense around those sorts of metrics, and do you agree with that?

Malgorzata, we certainly would agree with you on it. It's one of the reasons we get super excited about the whole relationship with Epic, and they've been just outstanding partners out of the gate here. So our excitement and enthusiasm, frankly, just continues to grow as we get closer to them. In terms of the work savings and the time savings from these integrations that we currently go through today, as you know, integration is a big part of our focus. Our goal is to get more than 50% of our accounts fully integrated with the EHR systems, which is a matter of many months of work that it takes both from our team and also the teams on the account side. And that's a big lift, both in terms of time, resources, as well as financial resources. With Aura, we expect that can start to be counted in a matter of weeks. For those accounts that are not Aura accounts, now for folks that ultimately are Epic accounts and adopt Aura, even if they're not a customer of ours today, we're going to end up right in their order set as a solution or offering without any incremental integration really required. And that really excites us because when you think about that, not only are we calling on the accounts and coming in through the front doors, but for these accounts that we haven't yet gotten to and they're already Epic Aura users, they're ultimately going to have access to our product as well. And so I think it only increases our odds of success and chances to win, which is why I do think it will be a needle mover for us and ultimately allow us to capture even more share as we go into the future. Now, over the course of '24, our work will continue with Epic as we design out what that interface looks like and what that order set looks like within their system and platform. We'll pilot that with the selected accounts that I've already mentioned in my prepared remarks here in the back part of the year, and then we'll really turn that on in early 2025 to begin to really expand the offering out across the broader universe. But I don't expect a significant contribution in '24. I think '25 could be a really exciting year when it comes to Epic and the Aura integration that we're working on.

The next question comes from Richard Newitter from Truist.

Maybe just a first one on the training and the onboarding that's going on in the San Francisco IDTF hires. I'm just curious where are you in terms of the throughput shift to that IDTF? And how much of what you're seeing in terms of their productivity improvements as we're moving through the quarter, how much of that increase will you think you'll see exiting the year in terms of what we can put through that region? And then if you could also speak to any implications for gross margin from that transition?

Rich, thanks for the question. I'll take that one. This is Brice. So I would say we're progressing nicely. Honestly, we talked about last quarter as we have that large investment in the fourth quarter. It takes about six to nine months for these individuals to get fully up to speed and start to optimize efficiently. And so I think we're sort of midway through. However, we're going to see some progress in Q2, and that's definitely more so in Q3 and Q4. So it's progressing nicely. As far as the volumes going through the IDTF, we talked about being slightly north of 60% exiting 2023. We're continuing to make progress on that and we feel good about the transition there. Having those resources allows us to do that. It's the center of excellence for us now, and we want to make sure we're servicing that patient population as effectively and efficiently as we possibly can. As you move into the back half of the year, the way I really think about the gross margin step-up from the 66% we're seeing now up to that 70% or so range in the back half, I think about that clinical technician efficiency in San Francisco contributing about 200 basis points. I think about the automation component of the Zio Monitor platform contributing about 100 basis points. And then I think about the scale as we continue to push Zio Monitor further into our in-clinic business and then ultimately followed by home enrollment, contributing about 100 basis points. We feel like all three are making progress in line with our expectations and feel good about the guidance we put out there.

The next question comes from Marie Thibault of BTIG.

Congrats on a very nice Q1. I wanted to ask a little bit more on guidance. You had a very nice quarter, and I know that was against the face of dealing with some weather disruption early in the quarter. Can you help us think about how you set that guide? Was there a little prudence baked in? How should we consider this new revenue range?

Yes. Marie, this is Brice again. Thanks for the question. I think what was important for us to do was to pass through the beat from the first quarter. We did talk about a little bit of disruption early on. However, we saw incredible recovery in the back half and continued momentum into Q2. And so the way we feel about guidance moving forward, we certainly have tailwinds at our back. We've talked a lot about them in Quentin's prepared remarks, as well as just the opportunity we have in front of us, and we feel good about it. But I'll tell you, when you look at the guidance setup, you're going to see growth rates that are relatively consistent at midpoint, and at the top end of the range, it does have growth accelerating. We absolutely believe that's achievable, and we feel great about it. However, it does take some execution, right? We're in the midst of the launch of the Zio Monitor product, and we're navigating the conversations with the FDA. It requires a commercial launch internationally. There are some things we have to execute on, and we truly believe we're going to be able to execute on all those. However, until we see that execution play through, we're going to be a bit softer on the guidance for the last three quarters of the year.

Your next question comes from Joanne Wuensch from Citibank.

Just a few catch up here. Where are you on the FDA warning letter resolution? Anything new on the Department of Justice? And what is the current thinking of timing for monitor for AT?

Joanne, thanks for the question. Look, from an FDA perspective, I would tell you, we continue to be really encouraged with the work that's going on with the FDA. I think the collaboration is as high as it's ever been. I applaud our own teams, but also applaud the FDA just with the approach here that the two sides have taken. Again, I couldn't feel better about it. I feel like we're making great progress with it. We originally had anticipated that we would see an approval sometime around the mid-part of the year. It's probably a couple, maybe a few months later behind that as we work through this and just go back and forth. My confidence level has never been higher that we're going to ultimately see an approval here. It's just a matter of the back and forth with the agency and making sure we're answering all those questions in a way that addresses the questions they have. So we feel good about the momentum there and the progress that's being made there. Again, I think getting the new MCT category code created, being the first product put into that category code, just continues to validate the progress that's being made, and I appreciate the relationship again with the agency. With respect to MCT, I continue to believe we'll get on file in the back half of this year with the agency. It's probably a little bit skewed towards the latter part of the back half of the year, but still expect to have MCT filed in the second half of 2024, which means we're bringing that product into the market in 2025. So excited with MCT. I'll remind you, when you think about growth levers in the future, we only have about 7% of that MCT marketplace despite the fact that we have about 70% of the long-term cardiac monitoring place. And every 10 points of growth that we can capture in that MCT space is pushing up on nearly $100 million of incremental revenue to us. So MCT is an important one, and we're very excited about the enhanced features that are going to come in that MCT product once we get it through. And then on the DOJ, not anything to update on at this point in time. We continue to answer questions when they come and provide information when the questions come. But there really hasn't been a lot of dialogue or back and forth here, and there's not much to update on at this point in time. Certainly, if that changes, and there is something to update on, we'll be sure to let you know, but there's just not a lot to update here.

The next question on the line comes from Kallum Titchmarsh of Morgan Stanley.

Just stick to MCT here, if that's okay. You alluded to about 7% share in this market for AT today. So realistically, I think after those first couple of years of launch of MCT, where do you think your share could move to in this market? Because it seems as though there are a couple of pretty small lightweight high-tech MCT devices coming through the market today from competitors. So I'm just curious what it is about your product that's encouraging you about a potential uptake here?

Yes. Look, how far we can get, Kallum. I think we're going to wait and see with the success that we have in the market. I think what's really fascinating, and one of the reasons that we believe we have a high degree of opportunity to win here, is the exact same customer call point that is prescribing long-term cardiac monitoring today in the way of Zio is also writing scripts for competitive MCT products because our product isn't quite what they're looking for. And I think we know very well why that is. One is the duration of wear, while the data is incredibly compelling with respect to why 14 days of monitoring is sufficient. I can tell you that data only continues to build. The customers want to see out to 30 days of monitoring or up to 30 days. And so we need to continue to work toward closing that gap. Frankly, we just need to continue to compel them with data as well, but we need to meet the customer where the customer wants to be met. And that's one of the things that we're doing in this enhanced MCT product. The other thing that a lot of our competitors will offer is a downgrade capability when insurance is not able to be found for the actual MCT device, can they step down into something like an event monitor? Those are capabilities that we're building into our products as well, and begin to eliminate the argument from a physician's perspective on why Zio MCT is not the right product for them. So whether we can get all the way to 70% of the MCT market like we have in long-term cardiac monitoring market, certainly, we're not setting our expectations that way, but there is a lot of room to run in there to capture market share and have success. So could you get half of that? It's hard to say. But if we're just picking up 10 points, that's an incremental $100 million of revenue to our company. I like our opportunities to get in there and compete for that and ultimately have success with it.

The next question comes from Nathan Treybeck of Wells Fargo.

Congrats on a great quarter. I don't think I heard you specifically call out your partnership with Signify Health in your opening remarks. Can you provide an update on where you stand currently? And are you still in pilot? And when do you expect the full rollout? And also Signify just announced the CEO transition. Does this impact your outlook from this partnership?

Nathan, I don't think it changes anything in terms of how we look at the partnership here. I made a comment in the prepared remarks, Q1 was very encouraging. We actually signed up several new innovative primary care partners in this space. We're excited about the collaboration with Signify. It is still in pilot phase, and we're still working through that, but we fully expect to turn that into a broader commercial launch in the back half of this year. So a little bit early to speak to the results at this point in time. I can tell you if we see results like we saw with some of the other innovative primary care players. I point back to PCC. We saw nearly 80% of the patients that were applied patches that were asymptomatic ultimately were found to have an arrhythmia. That is very informative, and I think allows these innovative channels to really address care the way they need to. So we're excited by the prospects of the Signify relationship. We're excited by the prospects of some of the other innovative primary care players that are coming into this. I think it validates our thesis that primary care is absolutely the place that this device is ultimately going to get applied into the future just with this ease of use. It's high diagnostic yield, it's incredible accuracy, and the ability to create tremendous workflow efficiencies. Ultimately, all of that comes back in play with respect to delivering incremental value and this whole focus on value-based care. I just really like the way that Zio is positioned to address this into the future. So we couldn't be more excited, but we're going to let that play out in the back half of the year. And hopefully, we're talking a whole lot more about it.

The next question comes from David Rescott of Baird.

Great. Congrats on a strong start to the year here. Brice, I just wanted to clarify one comment you made, and then I had a question for Quentin on Signify. Did you say that the percentage of volumes that came through San Francisco exiting 2023 were above 50% or above 60%? And then on Signify, for Quentin, I appreciate the comments you just provided there. But I'm wondering if you could frame up maybe the size of the opportunity there. I think the last that the company called out was about $3 million annual in-home evaluations. Wondering if you have a sense for how many of those are eligible for diagnostics, preventive services, and maybe therefore, at risk for A-fib, and then longer term and in the back half of the year into 2025. Beyond this initial rollout, I'm just trying to get a sense for how this rolls into patients. Is it more getting rolled out across these eligible patients, or is it more offered to the patients, and therefore, it's up to the patient to decide whether or not they want to participate in some type of program like this?

Yes, just a clarification, just north of 60% exiting 23 with continued progress in Q1 and expected progress throughout the rest of the year.

Yes. And I think, David, it's early right now. I can tell you, we've had a lot of discussions with Signify around what the potential opportunity can look like. I think we're still nailing that down. Probably the best way to describe it is you go back, you look at the mSToPS criteria, you look at some of the data that's out there around identifying arrhythmias in these comorbid conditions where other disease states are present, maybe it's diabetes, maybe it's COPD, maybe it's obesity. It's at least 25% or so of the population. And so if those rates apply to Signify, I think you can see that it's a pretty significant opportunity. The question is, is there more there? We know that this population tends to be one that needs care in the home, can't get out to see a physician. So does that mean that it's a little bit of a different population where those rates are even higher? We'll see as we go.

The next question comes from the line of Bill Plovanic from Canaccord.

Just wanted to take a step back just on the launch of Zio Monitor. Just one, you're seeing good uptake in new accounts. Are all new accounts getting Zio Monitor, and you're still transitioning just the existing accounts? Or where are you with that? And then in terms of the compliance rate, I think one of the things you saw early on was a higher compliance rate in returning the device. And I'm wondering if that is still carrying through?

Bill, it's Brice. So yes, on the rollout, that is absolutely the case. All new accounts coming on are starting with Zio Monitor. And we're approaching, call it, that 80% or so level of existing accounts also being converted. So the progress on Zio Monitor has gone incredibly well. But you have it right with thinking all new accounts are on it, and then existing accounts will slowly come up to speed here. As far as the compliance rate, you're absolutely right, there is a benefit to Zio monitor, much of which is related to the form factor, but also just the high diagnostic yield of the device and those coming back with data. We are seeing an improvement there. I will tell you there's a few dynamics at play here. Home enrollment ticking up a little bit. Compliance tends to be a little bit lower there. And as PCP and some other of these alternative channels come into place, there's a little bit different return dynamic for those. However, once everyone is on monitor, we feel really good about that return device rate improving nicely over the time horizon.

The final question today comes from Suraj Kalia from Oppenheimer.

I have a quick question for you, Quentin, regarding sleep. I'm curious why sleep is a focus given that obstructive sleep apnea is fairly predictable, and the algorithms involved are relatively simple compared to atrial fibrillation, which is much more complex. I'm trying to understand what value you see in this area. And Brice, if I could ask another quick question about the SFO IDTF. Has a decision been made regarding the situation? If you're currently at 60% capacity and expected to increase, there must be a trade-off between operational expenses and revenue. I'm interested in the current read-throughs per report for your technicians.

Thanks, Suraj. So I'll hit that first one on sleep. Look, I think the prevalence of OSA is incredibly high. And the reality is these patients need a diagnosis. And the further reality is that so many of them start with the cardiologists, the EP or even the primary care physician. Ultimately, they get referred on to a sleep specialist or they get a diagnosis performed right there by that cardiologist EP or a primary care physician. We have access to these very same customers. And as we sit down in our advisory groups with these customers and we ask for ways to streamline their practice or ways that we could add incremental value, consistently at the very top of the list, if not the absolute top of the list, is help us figure out how to deal with this cumbersome, challenging process that we have with our sleep patients. So many times, we'll refer them on to a sleep specialist. They can't be seen for 5, 6, 7 months. They get lost in the fray. They never get a diagnosis, and they're back in my office trying to figure out what is going on. With our call point, with our digital platform, ZioSuite being integrated right into the accounts, and our IDTF capabilities, we think it's a natural synergy and a very easy opportunity to enable these physicians to be able to prescribe a home sleep test, we send that device to the home just like we do in our home enrollment program. We leverage IDTF capabilities to perform the analysis and ultimately put a diagnosis back into the hands of the physician. You think about it, serving north of 2 million patients a year now, 60% to 70% of all patients who have A-fib will have OSA as well. There's a natural synergy here between what we do, what our customers are looking for, and what we're able to offer. So we're incredibly excited by it. I think it could be a tremendous opportunity for us.

Yes. Suraj, so a question on the CCTs and the San Francisco Center of Excellence. So remember, the CCT costs themselves run through gross margin, not through OpEx. The administrative component, there's a piece of it that resides down in OpEx, but the vast majority of that rolls through gross margin. And so I would say the read-throughs as they stand now, there's a little bit of inefficiency, which is causing the pressure on gross margin as it stands now, and that's that natural progression we expect in the back half of the year. Again, to the tune of about 200 basis points. There is no reason to believe the efficiency level will be any different in the Center of Excellence than what we would see in either one of the other two IDTFs over time. Frankly, we hired a tremendously talented group where you could see potential efficiency gains there over time. So again, we feel great about the gross margin playthrough over time. It's just going to take a little bit of time for them to get up to the efficiency levels that we see with the other IDTFs.

We have no further questions on the line, so I'll hand back to the management team for any closing remarks.

Well, thank you for joining us today. We're extremely pleased about the start to 2024 and couldn't be more excited about the growing momentum in our business as we begin to explore opening new adjacencies like sleep and continue to expand into the primary care channel. In the back half of the year set up to demonstrate significant financial leverage as we continue to progress in our efforts to become more operationally excellent as we grow. In addition, we have many catalysts to growth that remain in front of us, which are yet to contribute to our success, including a new innovative Zio MCT solution, entry into the second largest ACM market in the world in Japan, expanding further into primary care and stepping into adjacent sleep markets. iRhythm's future has truly never been brighter than it is today, and I'm grateful to each of our employees around the world as they're doing a great job in progressing our efforts forward. We'll see over the course of the next couple of months. Goodbye.

This concludes today's conference call. Thank you all for joining. You may now disconnect your lines.