A small adhesive wireless monitor worn on the chest for up to 2 weeks detected more arrhythmia events than a Holter monitor in a prospective study of 146 patients referred for evaluation.
The three-lead, 24-hour Holter monitor is the most commonly used method for investigating suspected arrhythmias in the ambulatory setting, but it has a diagnostic yield of just 15% to 39% in patients with palpitations, according to the study background.
Paddy M. Barrett, MB, BCh, BAO, of Scripps Translational Science Institute in La Jolla, Calif., and colleagues compared the diagnostic utility of the Holter monitor with that of an FDA-cleared, single-lead, 14-day ambulatory ECG adhesive patch monitor (Zio Patch, iRhythm Technologies Inc.).
The researchers outfitted patients (median age, 64 years; 41.8% men) referred to the cardiac investigations laboratory at Scripps Green Hospital between April and July 2012 with the adhesive patch monitor and a 24-hour Holter monitor. Median wear time was 1 day for the Holter monitor and 11 days for the adhesive patch monitor.
The primary outcome was detection of arrhythmia events by both devices over total wear time. Arrhythmia events were defined as one of the following: supraventricular tachycardia, atrial fibrillation/flutter, pause >3 seconds, atrioventricular block, ventricular tachycardia or polymorphic ventricular tachycardia/ventricular fibrillation.
Prolonged monitoring time
During the total wear time, the adhesive patch monitor detected 96 arrhythmia events and the Holter monitor detected 61 (P>.001). Thirty-six events were detected by the adhesive patch monitor, but not the Holter monitor; one event was detected by the Holter monitor, but not the adhesive patch monitor. Researchers attributed the difference to the prolonged monitoring time for the adhesive patch monitor.
During the simultaneous 24-hour monitoring period, the adhesive patch monitor detected 52 arrhythmia events and the Holter monitor detected 61 (P=.013). Two events were detected by the adhesive patch monitor, but not the Holter monitor; 11 events were detected by the Holter monitor, but not the adhesive patch monitor. Of those 11 events, 10 were subsequently detected by the adhesive patch monitor after the initial 24-hour period. A root-cause analysis determined that two of the discrepancies were caused by an algorithm misclassification and seven were caused by a processing error by an iRhythm Technologies staff physician reviewer. Training has been implemented to correct the latter, according to the report.
When the researchers conducted an analysis excluding supraventricular tachycardias, the adhesive patch monitor detected 24 arrhythmia events during the simultaneous 24-hour monitoring period and the Holter monitor detected 27 (P=.083). All of the three events not detected by the adhesive patch monitor during the 24-hour period were detected by it subsequently.
Survey results from patients and attending physicians favored the adhesive monitoring patch. Of patients with complete survey data, 93.7% said the adhesive monitoring patch was comfortable to wear and 51.7% said the same of the Holter monitor. The adhesive patch monitor affected daily living activities of 10.5% of patients compared with 76.2% for the Holter monitor. When asked which monitor was preferred of the two, 81% of respondents preferred the adhesive patch monitor. Of the 102 attending physicians surveyed, 90% thought a definitive diagnosis was produced by the adhesive patch monitor and 64% thought one was produced by the Holter monitor.
“On the basis of these findings, novel, single-lead, prolonged duration, low-profile devices may soon replace conventional Holter monitoring platforms for the detection of arrhythmia events in patients referred for ambulatory ECG monitoring,” Barrett and colleagues wrote.
Disclosure: The study was funded in part by iRhythm Technologies Inc. The researchers report no relevant financial disclosures.