PITTSBURGH, PENNSYLVANIA. The reliable detection of abnormal heart rhythms is essential in diagnosis of arrhythmias and in follow-up after catheter ablations or surgery to correct arrhythmias. The most common methods for evaluating heart rhythms are the 12-lead electrocardiogram (ECG), 24-hour Holter monitoring, and patient-activated event recorders. Although each of these methods has proven effective in diagnosing arrhythmias, they are not practical for long term monitoring. Researchers at Harvard Medical School now report the results of a pilot study aimed at evaluating the merits of a new measuring device. The Zio Patch is a single-use, completely self-contained, noninvasive, waterproof, long-term continuous monitoring patch capable of monitoring heart rhythm for up to 14 days. The patch comes equipped with a trigger button that the patient can press if feeling symptoms of arrhythmia.

The Harvard study involved 74 patients, an average age of 65 years and 55% male, who had been referred for Holter monitoring for the evaluation of paroxysmal atrial fibrillation (AF). Between April 2011 and May 2012 the 74 patients (90% lone afibbers) were simultaneously outfitted with a standard 24-hour Holter monitor and a Zio Patch to determine the pattern of AF, document response to medical therapy, and to potentially diagnose other arrhythmias. During the initial 24-hour comparison period, the Holter monitor and the Zio Patch both recorded 25 AF episodes and the estimated AF burden associated with these episodes was comparable. After the first 24 hours, Holter monitoring was discontinued but patients continued to wear the Zio Patch for as long as possible (average of 11 days). In total, 454 patient days were recorded on the Patch during which time additional AF episodes were detected in 43 patients. In those without AF showing up on an ECG or the 24-hour Holter monitor, the median time to onset of first AF episode was 3.7 days and 90% of first AF events had occurred by day 7.

Overall, 41 patients (55.4%) used the trigger button on the Zio Patch because they felt an irregular heart rhythm. Of the total 305 triggered events, most (66%) showed that the patient was in normal sinus rhythm when using the button but 29% correlated with AF, 5% with supraventricular tachycardia, and 1% with pauses. In addition to AF episodes, the Zio Patch also identified PACs (supraventricular ectopy) in 24% of patients, PVCs (ventricular ectopy) in 34%, and supraventricular tachycardia in 5% of patients. As a result of completing the Zio Patch study, 21 patients had a change in their AF management protocol – most often involving a change in antiarrhythmic medication.

The researchers conclude that the Zio Patch is well tolerated and allows for significantly longer, continuous monitoring periods resulting in improved clinical management including the detection of asymptomatic episodes.
Rosenberg, MA, et al. Use of a noninvasive continuous monitoring device in the management of atrial fibrillation. PACE, Vol. 36, March 2013, pp. 328-33

Editor's comment: The Zio Patch, although needing further study, would appear to be a most welcome addition to the methods currently available for heart rhythm monitoring. I found it particularly interesting that, in most cases (66%), when a patient felt irregular heart beats they were actually in normal sinus rhythm. This indicates, perhaps not surprisingly, that there is a major psychological component in AF.