The Zio Patch is a small, adhesive, single-use heart monitor that sticks to your chest and continuously records your heart’s electrical activity for up to 14 days. Unlike a traditional Holter monitor, which typically runs for just 24 to 48 hours and requires multiple wires and electrodes, the Zio Patch captures a single-channel electrocardiogram (ECG) around the clock, stores every heartbeat, and then uses artificial intelligence to analyze the data and produce a detailed report for your doctor. That combination of extended wear time and automated analysis is what makes it useful for catching heart rhythm problems that come and go unpredictably.
What the Patch Actually Is
The Zio Patch is roughly the size of a large adhesive bandage. It has no dangling wires or visible electrodes. You wear it on your upper left chest, and it adheres directly to the skin using a medical-grade adhesive. Inside that small housing is a single-channel ECG recorder with up to 14 days of memory storage capacity.1Progress in Cardiovascular Diseases. ECG Patch Monitors for Assessment of Cardiac Rhythm Abnormalities “Single-channel” means it records from one electrical perspective across your chest, as opposed to the 12 different angles a full hospital ECG uses. That single channel is enough to identify rhythm abnormalities, which is the patch’s primary job. It is also waterproof, so you can shower with it on, though swimming and submerging for long periods is generally discouraged.
The device has one button on its surface. When you feel symptoms like palpitations, dizziness, or a racing heart, you press that button to mark the moment. The patch logs the time of the press so that later, analysts can line up what you felt with what your heart was doing at that exact moment. After the monitoring period ends, you mail the patch back to the manufacturer in a prepaid envelope. The data then goes through a processing pipeline that combines automated AI analysis with human review by certified cardiac technicians.
What Gets Recorded and Stored
Every beat of your heart for the entire wear period is captured and stored on the device. This is continuous recording, not triggered recording. Older event monitors required you to press a button or relied on a built-in algorithm to decide when to start saving data; if nothing triggered the device, those intervals were lost. The Zio Patch does not work that way. It saves everything, which means even brief, symptom-free episodes of abnormal rhythm that last only a few seconds are preserved in the recording.
The types of abnormal rhythms the patch is designed to catch include atrial fibrillation (an irregular, often fast heart rhythm originating in the upper chambers), supraventricular tachycardia (fast heart rates arising above the ventricles), ventricular tachycardia (fast rhythms from the lower chambers, which can be dangerous), pauses in the heartbeat, and various types of premature or extra beats. A systematic review across 22 studies found that the Zio system detected atrial fibrillation in about 12% of patients monitored, supraventricular tachycardia or premature beats in roughly 46%, and ventricular tachycardia in about 17%.2PubMed. Cardiac arrhythmia detection outcomes among patients monitored with the Zio patch system: a systematic literature review Those rates vary depending on why the patient was being monitored in the first place, but they give a sense of how broadly the device casts its net.
How Artificial Intelligence Processes the Data
Two weeks of continuous heart rhythm data amounts to an enormous volume of ECG tracing. No human could efficiently review all of it beat by beat. iRhythm, the company behind the Zio Patch, developed a deep neural network (a type of AI) that is FDA-cleared to classify arrhythmias from single-lead ECG recordings. In validation testing using over 91,000 single-lead ECGs from more than 53,000 patients, the algorithm outperformed board-certified cardiologists in classifying atrial fibrillation, achieving a sensitivity of about 86% compared with roughly 71% for the cardiologists.3Frontiers in Signal Processing. Horizons in Single-Lead ECG Analysis From Devices to Data Sensitivity here means the proportion of true atrial fibrillation episodes the system correctly identified.
The AI does not replace human oversight. After the algorithm flags and classifies segments of the recording, certified cardiographic technicians review the flagged events and confirm or correct the classifications. The result is a curated report that combines machine speed with human judgment. iRhythm also offers a version called the Zio AT, which transmits data in near-real time so clinicians can be alerted to urgent rhythms before the monitoring period ends, rather than waiting for the patch to be mailed back.3Frontiers in Signal Processing. Horizons in Single-Lead ECG Analysis From Devices to Data
What the Final Report Looks Like
The report your doctor receives is not a stack of ECG tracings. It is a structured summary designed to be clinically actionable. Key elements include the types of arrhythmias detected, representative ECG strips for each event, the total number and duration of episodes, heart rate trends over the monitoring period, and a calculation of atrial fibrillation burden if AF was present.
AF burden is a particularly important metric. It represents the percentage of total monitoring time your heart spent in atrial fibrillation. In one study of patients with known AF, the Zio Patch reported an overall mean AF burden of about 28% across the monitoring period.4PubMed Central. Use of a Noninvasive Continuous Monitoring Device in the Management of Atrial Fibrillation: A Pilot Study That number matters because AF burden is linked to stroke risk. A separate study using Zio-derived data in patients with paroxysmal AF found a median AF burden of about 4%, with the longest continuous episodes lasting a median of roughly three hours.5JAMA Cardiology. Association of Burden of Atrial Fibrillation With Risk of Ischemic Stroke in Adults With Paroxysmal Atrial Fibrillation Knowing how much time a patient spends in AF helps doctors decide whether blood thinners or other treatments are warranted, and how aggressively to pursue rhythm control.
When comparing the patch’s AF burden measurement against a simultaneously worn Holter monitor during the first 24 hours, the two devices showed strong agreement, with a correlation of 0.96.4PubMed Central. Use of a Noninvasive Continuous Monitoring Device in the Management of Atrial Fibrillation: A Pilot Study The patch’s AF burden estimates are considered reliable enough to guide clinical decisions.
Why the Symptom Button Matters
One of the report’s more underappreciated features is the symptom-rhythm correlation. Every time you press the button, the system checks whether an arrhythmia was happening at that moment. This correlation tells your doctor whether the palpitations or lightheadedness you’ve been experiencing are actually caused by a rhythm problem or by something else entirely.
A large retrospective study of over a million patients wearing patch-based monitors found that overall symptom-rhythm correlation was about 18%. The correlation was highest for atrial fibrillation and isolated premature beats, where it exceeded 30%, but fell below 15% for other rhythm types.6Heart Rhythm. Relationship of symptom frequency and symptom-rhythm correlation to arrhythmia type and time to detection: Insights from ambulatory electrocardiogram monitoring in over 1 million patients Patients who experienced symptoms daily had substantially higher odds of achieving a meaningful correlation than those with less frequent symptoms. In practical terms, this means that if your symptoms are rare, the patch might still catch an arrhythmia somewhere in the 14-day window, but linking it to the specific moment you feel something may be harder.
Why 14 Days Catches What Shorter Monitors Miss
The extended monitoring window is one of the Zio Patch’s biggest advantages. Many arrhythmias are intermittent. A person might go days without an episode and then have a cluster. A standard 24-hour Holter monitor simply does not watch long enough. In a head-to-head comparison, the Zio Patch detected 96 arrhythmia events over its full wear period compared with 61 events picked up by a simultaneously worn Holter.7PubMed Central. Comparison of 24-hour Holter monitoring with 14-day novel adhesive patch electrocardiographic monitoring
The gap is especially stark for atrial fibrillation. In one study, atrial fibrillation lasting 30 seconds or longer was detected in 6% of patients wearing the Zio Patch, compared with 0% of those monitored by a 24-hour Holter. Nonsustained ventricular tachycardia showed up in 24% of Zio patients versus 8% with Holter.8PubMed. Diagnostic Yield, Outcomes, and Resource Utilization With Different Ambulatory Electrocardiographic Monitoring Strategies Research has confirmed that the patch continues to find new arrhythmias well past the 48-hour mark, which means cutting the monitoring short would mean missing diagnoses.9The American Journal of Cardiology. Diagnostic Utility of a Novel Leadless Arrhythmia Monitoring Device
Wearing It for the Full Two Weeks
A 14-day monitor only works if people actually wear it for 14 days. Studies consistently show high compliance with the Zio Patch. Patients generally find it more comfortable and less intrusive than a traditional Holter, largely because there are no wires and the device is small enough to hide under clothing. The most common reason for early removal is loss of adhesive, which accounted for about 11% of cases in one study examining compliance patterns.10PubMed Central. Identifying Demographic Factors Affecting the ECG Duration Collected Using a Single-Lead ECG Patch Device
Body size matters for adhesion. Higher body mass index was independently linked to shorter wear times in the same study, with the adhesive more likely to peel off in patients with a larger body habitus.10PubMed Central. Identifying Demographic Factors Affecting the ECG Duration Collected Using a Single-Lead ECG Patch Device Skin preparation before application, including cleaning the area with alcohol and making sure it is dry, can help the patch stick longer. Some people develop mild skin irritation under the adhesive, which is generally manageable but occasionally leads to early removal.
Searching for Hidden Atrial Fibrillation After a Stroke
One of the patch’s most consequential uses is in patients who have had a stroke or transient ischemic attack (TIA) without an obvious cause. These events are sometimes called cryptogenic strokes, and a significant minority turn out to be caused by undiagnosed atrial fibrillation that was not caught during the hospital stay. Finding AF in these patients changes management dramatically because anticoagulation therapy can prevent a second stroke.
In a study of stroke and TIA patients monitored with the Zio Patch, the frequency of newly detected AF reached about 5% over 14 days of monitoring. Most first episodes of paroxysmal AF appeared quickly, with a median time to first detection of less than a day, but about 14% of first episodes were not detected until after 48 hours.11Frontiers in Neurology. Diagnostic Yield of Extended Cardiac Patch Monitoring in Patients with Stroke or TIA Another systematic review of wearable technology after cryptogenic stroke confirmed similar detection rates, with about 4% of patients found to have paroxysmal AF lasting at least 30 seconds, and ventricular tachycardia showing up in over 13%.12PubMed Central. Use of wearable technology in cardiac monitoring after cryptogenic stroke or embolic stroke of undetermined source: a systematic review These findings reinforce why extended monitoring is now part of standard workup after unexplained strokes.
Use in Children
The Zio Patch is not limited to adults. Pediatric cardiologists have increasingly adopted it for children and adolescents, particularly because kids tend to tolerate the small adhesive patch better than a bulky Holter harness. One study found that the patch can be used in pediatric patients across all ages, though older children tended to achieve longer monitoring durations than younger ones. Critically, the majority of arrhythmias detected were identified after the first 24 hours, meaning they would have been missed entirely by a standard short-term monitor.13PubMed. Ambulatory Arrhythmia Detection with ZIO® XT Patch in Pediatric Patients: A Comparison of Devices
In a separate study of previously healthy children who were found to have nonsustained ventricular tachycardia on their Zio recordings, about 19% ultimately received a new cardiac diagnosis, including supraventricular tachycardia and suspected cardiomyopathy.14Heart Rhythm. Non-sustained ventricular tachycardia on 14-day Zio monitor in previously healthy pediatric population For families dealing with a child who has unexplained fainting spells or palpitations, the patch can provide answers without significantly disrupting the child’s daily routine.
Impact on Healthcare Resources
Beyond the clinical benefits, the Zio Patch has implications for how efficiently healthcare systems use their time and money. Because the device is mailed directly to the patient and mailed back for analysis, it eliminates the need for in-office Holter hookups and the staff time required to read traditional recordings. A cost-benefit analysis found that Zio XT use was associated with fewer outpatient appointments, fewer implantable loop recorder insertions (a more invasive option for long-term monitoring), and less time spent by cardiac physiologists on fitting and manual rhythm analysis.15PubMed Central. Zio XT for ambulatory heart rhythm monitoring: a cost-benefit analysis
For population-level AF screening, a cost-effectiveness analysis based on the mSToPS trial estimated that monitoring with the Zio Patch cost roughly $36,000 per quality-adjusted life year gained, with a roughly 64% probability of being cost-effective at a willingness-to-pay threshold of $50,000 per quality-adjusted life year.16PubMed Central. Cost-Effectiveness of AF Screening With 2-Week Patch Monitors: The mSToPS Study Those numbers place patch-based monitoring in a reasonable range compared with many accepted medical interventions, though whether large-scale screening of asymptomatic people makes sense remains debated. The evidence is strongest for patients who already have symptoms or who have had a stroke of unknown cause, where finding AF directly changes treatment.
What the Patch Cannot Do
For all its strengths, the Zio Patch has clear limitations worth understanding. It records a single ECG channel, which is excellent for rhythm analysis but not sufficient for diagnosing structural problems like heart attacks, which typically require a full 12-lead ECG. If your doctor suspects a blockage or acute coronary event, the Zio Patch is not the right tool.
The patch also cannot monitor blood pressure, oxygen levels, or other vital signs. It is purely an electrical rhythm recorder. And while 14 days covers a much wider window than a Holter, some arrhythmias are so infrequent that they still do not appear in two weeks. For patients whose episodes happen months apart, an implantable loop recorder, which sits under the skin and monitors for up to three years, may be the better choice. The Zio Patch fills a specific middle ground: longer than a Holter, less invasive than an implant, and well suited for arrhythmias that occur at least every couple of weeks. Understanding where it fits in that spectrum is the key to knowing whether it is the right monitor for a given situation.