Compliance high among patients with wearable cardioverter defibrillator

In addition to showing high rates of patient compliance, new study data suggested that survival and mortality rates were similar among patients with a wearable cardioverter defibrillator and those with an implantable cardioverter defibrillator.

Data from 3,569 patients who wore a wearable defibrillator for at least one day from August 2002 through December 2006 were collected from the device manufacturer’s database. Baseline data were available for 2,731 patients. The researchers compared survival among these patients with a cohort who had an ICD implanted at the Cleveland Clinic. Primary outcomes included patient compliance and efficacy of the wearable defibrillator as treatment for arrhythmia.

Median daily use was 21.7 hours (91% of time available) and mean duration of use was 52.6 ± 69.9 days (range 1 to 1,590 days). Daily use was >90% in 52% of patients and >80% in 71%, and more days of use correlated with higher daily use (P<.001). Discomfort or adverse reactions — mainly the weight and size of the device — resulted in discontinued use among 14.2% of patients.

Eighty sustained ventricular tachycardia/ventricular fibrillation (VT/VF) events occurred in 59 patients during wearable defibrillator use; 8 deaths occurred after conversion of unconscious VT/VF. During wearable defibrillator use, overall acute survival was 99.2% (3,541 of 3,569 patients) with 0.78% mortality due to sudden death over mean usage of 53 days, according to the researchers. Survival was 90% for VT events and 73.6% for all events, including non-VT/VF events.

Sudden death mortality occurred in patients not wearing the device, who had bystander interference electrocardiogram signal disruption or unipolar pacing artifacts, according to the researchers. In addition, 24.5% of sudden cardiac arrest events with high mortality rates were caused by asystole or pulseless electrical activity.

“Patient instruction regarding proper usage of and compliance with the wearable defibrillator is vital to ensuring the efficacy of the wearable defibrillator in preventing sudden cardiac death,” the researchers wrote.

In an accompanying editorial, Ralph J. Verdino, MD, of the Hospital of the University of Pennsylvania noted that the study contained some flaws, including missing information regarding patient demographics and treatment indications, but also acknowledged the observed efficacy of the device.

“It has a high degree of success in treating ventricular tachyarrhythmia and does not appear to be very cumbersome for patient use. Not prescribing this lifesaving attire to your high-risk patient awaiting ICD implantation or reimplantation is the real faux pas.”

Chung M. J Am Col Cardiol. 2010;56:194-203.

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