Cardiac arrhythmias are common, but can be difficult to diagnose due to their sparse and fleeting occurrences. Since the 1960s, the gold standard for their diagnoses has been the Holter monitor, a “portable” ECG-type device with 5 to 7 leads connected to a central processing unit, which continuously records electrical cardiac activity to help spot abnormal signals over an extended time period. Due to its bulky size and numerous leads, the Holter monitor has been a nuisance for its wearers. Researchers at the Scripps Translational Science Institute (STSI) have published a study that shows the small, wearable wireless ZIO Patch (iRhythm Technologies, San Francisco, CA) is better at diagnosing arrhythmias than the bulky Holter monitor, and also preferred by patients, potentially paving a new way for ambulatory heart monitoring.

The FDA-cleared ZIO Patch is a small, adhesive, water-resistant one lead ECG sensor that the user can stick onto their chest for a continuous 24-hour monitoring over 2 weeks. It sports hydrogel electrodes for clearer ECG tracings and a button to capture symptomatic events. At the end of the 2 weeks, the patch must be sent back to iRhythm for a full analysis using the ZIO Service’s proprietary algorithms, and a diagnostic report is then relayed to the patient’s physician.

In the current study, the researchers collected data from 146 patients who were equipped with both a Holter monitor for 24 hours, and a ZIO Patch for 2 weeks. They found that the ZIO Service detected 96 arrhythmia events, while the Holter monitor detected 61. An arrhythmia event was defined to be 1 of 6 types: “supraventricular tachycardia (>4 beats, not including atrial fibrillation or flutter), atrial fibrillation/fluter (>4 beats), pause >3 seconds, atrioventricular block (Mobitz type II or third-degree atrivoventricular block), ventricular tachycardia (>4 beats), or polymorphic ventricular tachycardia/ventricular fibrillation”.

From the STSI press release:

Physicians who reviewed data from both devices reported reaching a definitive diagnosis 90 percent of the time when using the patch results and 64 percent of the time when using Holter monitor data. A survey of study participants found that 81 percent of them preferred wearing the patch over the Holter monitor, with 76 percent saying the Holter monitor affected their daily living activities. One unexpected finding was that the Holter monitor detected 11 more arrhythmias than the ZIO Service during the initial 24 hour period when both devices were working simultaneously. However, all of those arrhythmias were picked beyond 24 hours by the patch during the device’s extended monitoring period. The ZIO Service detected two arrhythmias not captured by the Holter during the initial 24 hour period.

Press release: Patch Outperforms Holter for Prolonged Heart Rhythm Tracking…

Paper in the The American Journal of Medicine: Comparison of 24-hour Holter Monitoring with 14-day Novel Adhesive Patch Electrocardiographic Monitoring

Product page: ZIO…

Flashbacks: Medgadget Exclusive Interview with iRhythm’s CEO Kevin King; Zio Patch Wins Medical Design Award