iRhythm Unveils New Real-World Data at ACC.25 Demonstrating the Benefits of Zio® Long-Term Continuous Monitoring for Arrhythmia Detection
iRhythm Technologies (NASDAQ:IRTC) presented significant findings from two large real-world studies at ACC.25, analyzing over 1.1 million patients using Zio® long-term continuous monitoring (LTCM) devices. The research revealed critical limitations in traditional 24-48 hour Holter monitoring.
Key findings show that 64% of actionable arrhythmias in patients with daily symptoms went undetected in the first 48 hours of monitoring. Non-daily symptom patients showed higher arrhythmia yield (80.9%) compared to daily-symptom patients (69.1%). The study also found that less than 20% of patients documented symptoms coinciding with arrhythmic episodes, and over half of atrial fibrillation cases were asymptomatic.
The research challenges conventional monitoring approaches and supports the benefits of Zio LTCM's extended 14-day monitoring period. With approximately 16 million Americans experiencing arrhythmias and undiagnosed atrial fibrillation costing the U.S. $3 billion annually, these findings have significant implications for clinical care and payer policies.
iRhythm Technologies (NASDAQ:IRTC) ha presentato risultati significativi da due ampi studi reali all'ACC.25, analizzando oltre 1,1 milioni di pazienti che utilizzano dispositivi di monitoraggio continuo a lungo termine Zio®. La ricerca ha rivelato limitazioni critiche nel monitoraggio tradizionale Holter di 24-48 ore.
I risultati chiave mostrano che il 64% delle aritmie trattabili in pazienti con sintomi quotidiani è rimasto non rilevato nelle prime 48 ore di monitoraggio. I pazienti senza sintomi quotidiani hanno mostrato un rendimento di aritmia più elevato (80,9%) rispetto ai pazienti con sintomi quotidiani (69,1%). Lo studio ha anche scoperto che meno del 20% dei pazienti ha documentato sintomi coincidenti con episodi aritmici, e oltre la metà dei casi di fibrillazione atriale erano asintomatici.
La ricerca sfida gli approcci di monitoraggio convenzionali e supporta i benefici del periodo di monitoraggio esteso di 14 giorni dello Zio LTCM. Con circa 16 milioni di americani che sperimentano aritmie e la fibrillazione atriale non diagnosticata che costa agli Stati Uniti 3 miliardi di dollari all'anno, questi risultati hanno implicazioni significative per la cura clinica e le politiche dei pagatori.
iRhythm Technologies (NASDAQ:IRTC) presentó hallazgos significativos de dos grandes estudios del mundo real en ACC.25, analizando a más de 1.1 millones de pacientes que utilizan dispositivos de monitoreo continuo a largo plazo Zio®. La investigación reveló limitaciones críticas en el monitoreo tradicional Holter de 24-48 horas.
Los hallazgos clave muestran que el 64% de las arritmias tratables en pacientes con síntomas diarios no fueron detectadas en las primeras 48 horas de monitoreo. Los pacientes sin síntomas diarios mostraron un rendimiento de arritmia más alto (80.9%) en comparación con los pacientes con síntomas diarios (69.1%). El estudio también encontró que menos del 20% de los pacientes documentaron síntomas coincidiendo con episodios arítmicos, y más de la mitad de los casos de fibrilación auricular fueron asintomáticos.
La investigación desafía los enfoques de monitoreo convencionales y apoya los beneficios del período de monitoreo extendido de 14 días del Zio LTCM. Con aproximadamente 16 millones de estadounidenses experimentando arritmias y la fibrilación auricular no diagnosticada costando a EE.UU. 3 mil millones de dólares anuales, estos hallazgos tienen implicaciones significativas para la atención clínica y las políticas de los pagadores.
iRhythm Technologies (NASDAQ:IRTC)는 ACC.25에서 Zio® 장기 연속 모니터링(LTCM) 장치를 사용하는 110만 명 이상의 환자를 분석한 두 개의 대규모 실제 연구 결과를 발표했습니다. 이 연구는 전통적인 24-48시간 홀터 모니터링의 중요한 한계를 드러냈습니다.
주요 결과는 일일 증상이 있는 환자에서 감지되지 않은 치료 가능한 부정맥의 64%가 모니터링의 첫 48시간 동안 발견되지 않았음을 보여줍니다. 비일일 증상 환자는 일일 증상 환자(69.1%)에 비해 더 높은 부정맥 발생률(80.9%)을 보였습니다. 연구는 또한 환자의 20% 미만이 부정맥 에피소드와 일치하는 증상을 기록했으며, 심방세동 사례의 절반 이상이 무증상이었습니다.
이 연구는 기존 모니터링 방법에 도전하며 Zio LTCM의 14일 연장 모니터링 기간의 이점을 뒷받침합니다. 약 1,600만 명의 미국인이 부정맥을 경험하고 진단되지 않은 심방세동이 미국에 연간 30억 달러의 비용을 초래하고 있는 상황에서, 이러한 발견은 임상 치료 및 지불 정책에 중대한 의미를 갖습니다.
iRhythm Technologies (NASDAQ:IRTC) a présenté des résultats significatifs de deux grandes études réelles lors de l'ACC.25, analysant plus de 1,1 million de patients utilisant des dispositifs de surveillance continue à long terme Zio®. La recherche a révélé des limitations critiques dans la surveillance traditionnelle Holter de 24 à 48 heures.
Les résultats clés montrent que 64% des arythmies actionnables chez les patients présentant des symptômes quotidiens sont restées non détectées au cours des 48 premières heures de surveillance. Les patients sans symptômes quotidiens ont montré un rendement en arythmie plus élevé (80,9%) par rapport aux patients avec symptômes quotidiens (69,1%). L'étude a également révélé que moins de 20% des patients avaient documenté des symptômes coïncidant avec des épisodes arythmiques, et plus de la moitié des cas de fibrillation auriculaire étaient asymptomatiques.
La recherche remet en question les approches de surveillance conventionnelles et soutient les avantages de la période de surveillance prolongée de 14 jours du Zio LTCM. Avec environ 16 millions d'Américains souffrant d'arythmies et la fibrillation auriculaire non diagnostiquée coûtant aux États-Unis 3 milliards de dollars par an, ces résultats ont des implications significatives pour les soins cliniques et les politiques des payeurs.
iRhythm Technologies (NASDAQ:IRTC) hat auf der ACC.25 bedeutende Ergebnisse aus zwei großen realen Studien vorgestellt, in denen über 1,1 Millionen Patienten untersucht wurden, die Zio®-Geräte zur langfristigen kontinuierlichen Überwachung (LTCM) nutzen. Die Forschung hat kritische Einschränkungen der traditionellen 24-48 Stunden Holter-Überwachung aufgezeigt.
Wichtige Ergebnisse zeigen, dass 64% der behandelbaren Arrhythmien bei Patienten mit täglichen Symptomen in den ersten 48 Stunden der Überwachung unentdeckt blieben. Patienten ohne tägliche Symptome zeigten eine höhere Arrhythmieausbeute (80,9%) im Vergleich zu Patienten mit täglichen Symptomen (69,1%). Die Studie ergab auch, dass wenigstens 20% der Patienten Symptome dokumentierten, die mit arrhythmischen Episoden übereinstimmten, und mehr als die Hälfte der Fälle von Vorhofflimmern asymptomatisch waren.
Die Forschung stellt die konventionellen Überwachungsansätze in Frage und unterstützt die Vorteile des verlängerten 14-tägigen Überwachungszeitraums von Zio LTCM. Da etwa 16 Millionen Amerikaner Arrhythmien erleben und unentdecktes Vorhofflimmern den USA jährlich 3 Milliarden Dollar kostet, haben diese Ergebnisse erhebliche Auswirkungen auf die klinische Versorgung und die Richtlinien der Kostenträger.
- Large-scale validation with over 1.1 million patient data points
- Superior detection rate compared to traditional Holter monitoring
- Evidence supporting extended monitoring period effectiveness
- Strong clinical evidence base with 125+ research manuscripts
- Demonstrated higher diagnostic yield for non-daily symptom patients (80.9%)
- Current payer policies still favor traditional 24-48 hour Holter monitoring
- Over half of atrial fibrillation cases are asymptomatic, challenging detection
- Low symptom-rhythm correlation (less than 20%) may affect patient compliance
Insights
iRhythm's new clinical evidence represents a significant competitive advantage in the cardiac monitoring space. The real-world data from over 1.1 million patients directly challenges current clinical practice and payer policies that favor shorter-duration Holter monitoring. By demonstrating that 64% of actionable arrhythmias in daily-symptom patients go undetected in the first 48 hours, iRhythm creates a compelling case for its 14-day Zio monitoring solution.
This data strategically positions iRhythm to capture more of the substantial arrhythmia market, which affects approximately 16 million Americans. The financial implications are considerable, with undiagnosed atrial fibrillation alone costing the US healthcare system an estimated
For investors, the timing is particularly relevant as healthcare systems increasingly adopt value-based care models where improved diagnostic accuracy translates to financial incentives. These findings provide powerful ammunition for favorable reimbursement decisions, typically a key driver for medical device adoption and revenue growth.
With this evidence strengthening their already substantial clinical portfolio of over 125 published manuscripts, iRhythm is solidifying its scientific leadership position while creating concrete differentiation from competitors. The data effectively positions Zio LTCM as potentially the new gold standard, which could accelerate market share gains against legacy monitoring approaches.
These findings fundamentally challenge longstanding clinical assumptions about arrhythmia detection. The revelation that
The data on Symptom-Rhythm Correlation (SRC) is particularly striking - fewer than
The counter-intuitive finding that non-daily symptom patients had higher arrhythmia yield (
For electrophysiologists and cardiologists, this evidence creates a strong clinical imperative to use longer-duration monitoring regardless of symptom frequency. With atrial fibrillation being asymptomatic in over half of cases detected, and the mean time to first episode exceeding 48 hours across all arrhythmia types, the data suggests that 14-day monitoring should become the standard approach rather than the exception for patients with suspected arrhythmias.
Two large studies of over one million patients reveal that short-term Holter-duration monitoring frequently misses actionable arrhythmias and that patient-reported symptoms are an unreliable predictor of arrhythmic events
SAN FRANCISCO, March 31, 2025 (GLOBE NEWSWIRE) -- iRhythm Technologies, Inc. (NASDAQ:IRTC) today announced results from two large real-world retrospective analyses presented at the American College of Cardiology (ACC) 2025 Scientific Sessions in Chicago, IL. Drawing on data from more than 1.1 million patients who used iRhythm’s Zio® long-term continuous monitoring (LTCM) ECG devices, these studies demonstrate that short-term (24–48-hour) monitoring, such as with Holter devices, fails to detect a significant proportion of actionable arrhythmias—even in patients reporting “daily symptoms”—and that Symptom–Rhythm Correlation (SRC) is notably low for most arrhythmias, underscoring that selection of monitoring duration based on the frequency of symptoms alone can lead to undetected (missed) actionable1 arrhythmias. Together, these findings highlight the benefits of Zio® long-term continuous monitoring (LTCM)2 and the limitations in 24–48-hour Holter monitoring still prevalent in current clinical practices and payer policies.
Zio LTCM “Daily Symptoms” Study: Gaps in Short-Term Holter Monitoring
64% Undetected in the First 48 Hours: Among daily-symptom patients—those with daily or greater symptom frequency— diagnosed with actionable arrhythmias, nearly two-thirds went undetected through two days monitoring—indicating that 24–48-hour monitoring, such as with Holter, would have failed to detect them.- Higher Yield for Non-Daily Symptom Patients: Non-daily symptom patients—those with symptoms occurring with a frequency less than once per day—had an
80.9% arrhythmia yield versus69.1% in daily-symptom patients, demonstrating that greater symptom frequency does not necessarily reflect increased arrhythmia burden. - Mean Time to First Episode Exceeds 48 Hours: Across all arrhythmia types, the mean time to the first detected episode was greater than 48 hours—regardless of symptom frequency—underscoring the limitations of short-term monitoring.
Zio LTCM “Symptom–Rhythm Correlation (SRC)” Study: Symptoms Alone Are Unreliable
- Less Than
20% Correlation: In most arrhythmia types, fewer than one in five patients in the analysis documented a symptom coinciding with an arrhythmic episode. Symptom-rhythm correlation was higher for patients reporting daily vs. non-daily symptoms. - AF Often Asymptomatic: Even for atrial fibrillation (AF)—the most commonly symptomatic arrhythmia—over half of all cases were asymptomatic.
- Serious Arrhythmias Frequently Not Correlated with Symptoms: Ventricular tachycardia, AV block, and significant pauses were frequently detected by Zio LTCM without patient-reported symptoms, suggesting that selection of monitor duration should not be based on symptom frequency alone, and that long-term continuous monitoring may offer advantages over other monitoring types with shorter duration or those which rely on patient triggered events to initiate recording.
“These findings challenge the long-held assumption that frequent symptoms justify short-duration monitoring,” said Mintu Turakhia, MD, iRhythm Chief Medical and Scientific Officer and EVP of Product Innovation. “They reinforce the limitations of Holter-duration monitoring and highlight the value of Zio long-term continuous monitoring up to 14 days. Once again, iRhythm’s real-world data are contributing evidence that can help guide both clinical practice and payer policy.”
Arrhythmias: A Growing Burden for Patients and Health Systems
Up to five percent of the general population—around 16 million Americans—experience arrhythmias,3 in which the heart may beat too quickly, too slowly, or sporadically. If left untreated, certain arrhythmias can damage the heart, brain, or other organs4 and increase the risk of stroke or death.5,6,7 Beyond these clinical concerns, the financial toll of undiagnosed arrhythmias is substantial. It’s estimated that undiagnosed atrial fibrillation alone costs the U.S.
Implications for Clinical Care and Payer Policy
While 24–48-hour Holter monitoring is widely used in current clinical practice and historically supported by payer policies—especially for patients reporting daily symptoms—these new findings indicate that
New Data Add to iRhythm’s Clinical Evidence Base for LTCM
These new data build on iRhythm’s comprehensive clinical evidence program, encompassing more than 125 original research manuscripts,14 insights derived from over 2 billion hours of curated heartbeat data15 and more than 10 million patient reports posted since the company’s inception—underscoring the company’s ongoing commitment to expanding evidence that supports improved patient outcomes.
About the iRhythm Studies Presented at ACC.25
Holter monitoring of 24-48 hours remains in common use for patients with frequent or daily symptoms based on clinician or payer preferences. This retrospective cohort study sought to determine the percentage of arrhythmias detected by LTCM before and after 48 hours of monitoring in patients with daily (≥ 1/day) and non-daily (<1/day) symptoms. Researchers compared yield in patients ≥18 years prescribed a Zio® monitor or Zio® XT LTCM worn for >7 to 14 days from June 2023 to July 2024. These devices include a patient-activated button to document symptomatic episodes. Symptom frequency was measured as button presses/day and stratified by daily (≥1/day) or non-daily (<1/day). ECG data was analyzed via a deep-learned AI algorithm and confirmed by cardiographic technicians. Nearly two thirds (
Symptoms are the most common indication for ambulatory cardiac monitoring, yet Symptom–Rhythm Correlation (SRC) has not been well described across various arrhythmias. Researchers assessed SRC in patients ≥18 years who wore a Zio® monitor or Zio® XT LTCM for >7 to 14 days between June 2023 and July 2024. These devices include a patient-activated button to mark symptomatic episodes, and episodes within ±45 seconds of a recorded arrhythmia were considered rhythm-correlated. ECG data was analyzed via a deep-learned AI algorithm and confirmed by cardiographic technicians. Atrial fibrillation (AF) and ectopic beats were the rhythms most-correlated with patient symptoms. Overall symptom-rhythm correlation was low (i.e., <
About iRhythm Technologies
iRhythm is a leading digital health care company that creates trusted solutions that detect, predict, and prevent disease. Combining wearable biosensors and cloud-based data analytics with powerful proprietary algorithms, iRhythm distills data from millions of heartbeats into clinically actionable information. Through a relentless focus on patient care, iRhythm’s vision is to deliver better data, better insights, and better health for all. To learn more, please visit https://www.irhythmtech.com/.
Media Contact
Kassandra Perry
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1 Actionable Arrhythmias defined as Atrial Fibrillation ≥30 sec, Supraventricular Tachycardia ≥90 bpm & ≥30s, Ventricular Tachycardia ≥100 bpm & ≥4 beats, any Ventricular Fibrillation, Pause ≥3 sec, and/or Atrioventricular Block (any 2nd Degree or Complete Heart Block).
2 The Zio monitor is a prescription-only, single-use ECG monitor that continuously records data for up to 14 days. It is indicated for use on patients who may be asymptomatic or who may suffer from transient symptoms such as palpitations, shortness of breath, dizziness, lightheadedness, pre-syncope, syncope, fatigue, or anxiety.
3 Desai et al. Arrhythmias. In: StatPearls. Treasure Island (FL): StatPearls Publishing; June 5, 2023. https://pubmed.ncbi.nlm.nih.gov/32644349/
4 National Heart, Lung, and Blood Institute. Arrhythmias - What Is an Arrhythmia? www.nhlbi.nih.gov. Published March 24, 2022. Accessed April 25, 2024. https://www.nhlbi.nih.gov/health/arrhythmias
5 Ataklte et al. Meta-analysis of ventricular premature complexes and their relation to cardiac mortality in general populations. The American Journal of Cardiology. 2013;112(8):1263-1270. doi:10.1016/j.amjcard.2013.05.065
6 Lin et al. Long-term outcome of non-sustained ventricular tachycardia in structurally normal hearts. PLOS ONE. 2016;11(8). doi:10.1371/journal.pone.0160181
7 Wolf et al. Atrial fibrillation as an independent risk factor for stroke: The Framingham Study. Stroke. 1991;22(8):983-988. doi:10.1161/01.str.22.8.983
8 Turakhia et al. Economic Burden of Undiagnosed Nonvalvular Atrial Fibrillation in the United States. The American Journal of Cardiology. 2015;116(5):733-739. doi:https://doi.org/10.1016/j.amjcard.2015.05.045
9 Heidenreich et al. Forecasting the Impact of Heart Failure in the United States: A Policy Statement From the American Heart Association. Circulation: Heart Failure. 2013;6(3):606-619. doi:https://doi.org/10.1161/hhf.0b013e318291329a
10 Reynolds et al. Comparative effectiveness and healthcare utilization for ambulatory cardiac monitoring strategies in Medicare beneficiaries. Am Heart J. 2024;269:25–34. https://doi.org/10.1016/j.ahj.2023.12.002
11 A specified arrhythmia refers to an arrhythmia encounter diagnosis as per Hierarchical Condition Categories (HCC) 96.
12 Based on previous generation Zio XT device data. Zio monitor utilizes the same operating principles and ECG algorithm. Additional data on file.
13 Zio LTCM service refers to Zio XT and Zio monitor service.
14 Data on file. iRhythm Technologies, 2025.
15 Data on file. iRhythm Technologies, 2024.
FAQ
What percentage of arrhythmias were missed by 48-hour Holter monitoring according to iRhythm's IRTC study?
How does arrhythmia detection rate compare between daily and non-daily symptom patients for IRTC's Zio device?
What is the correlation rate between symptoms and actual arrhythmic episodes in IRTC's 2025 study?
How many patients were included in iRhythm's IRTC ACC.25 research studies?
What is the estimated cost impact of undiagnosed atrial fibrillation according to IRTC's research?
