High compliance, VT/VF survival with wearable cardioverter-defibrillators
MedWire News: A US study suggests that wearable cardioverter-defibrillators (WCD) produce high rates of patient compliance, and ventricular tachycardia (VT) and ventricular fibrillation (VF) survival rates similar to those achieved with implantable cardioverter defibrillators (ICD).
In the Journal of the American College of Cardiology, Mina Chung (Cleveland Clinic, Ohio) and colleagues comment: "Survival was comparable to that of ICD patients and highest in patients with traditional ICD indications, rationalizing the use of the WCD as an acceptable temporary alternative or a bridge to long-term ICD implantation."
Previous reports have suggested that patient compliance of the WCD may be limited by the potential inconvenience of wearing the vest. The researchers therefore investigated the level of compliance with and efficacy of the WCD among 3569 patients (mean age 59.3 years) using a WCD between August 2002 to December 2006.
The findings showed a high level of compliance among the participants with >80% daily use in 71% of patients. The mean duration of use was 52.5 days, at a mean rate of 21.7 hours per day (91% of time available).
In all, 80 sustained VT/VF events occurred in 59 patients. Efficacy of the WCD was high, with a 100% and 99% first-shock success rate for unconscious and all VT/VF events, respectively.
Survival following VT/VF events was 90.0% and overall survival for all events was 73.6% (78 out of 106 events); however 24.5% of these deaths were due to non-shockable events, pulseless electrical activity, or asystole.
The team explains that the other sudden deaths occurred when patients were not wearing the device, bystander interference with the device occurred, the electrocardiogram signal was disrupted due to body positioning, or a large pacing artifact arose from a unipolar pacemaker.
No significant survival difference was noted when survival rates with WCD use was compared with data for a group of patients implanted with ICD between 1996 and 2004.
The team conclude that the WCD is "an acceptable temporary alternative or a bridge to long-term ICD implantation," although they suggest that "patient instruction regarding proper use of and compliance with the WCD is vital in ensuring the efficacy of the WCD in preventing sudden cardiac death."
In an accompanying editorial, Ralph Verdino (University of Pennsylvania, Philadelphia, USA) adds: "Not prescribing this lifesaving attire to your high-risk patient awaiting ICD implantation is the real faux pas."
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By Lauretta Ihonor