Causes and clinical consequences of inappropriate shocks experienced by patients wearing a cardioverter-defibrillator

Background: The LifeVest® wearable cardioverter-defibrillator (WCD) prevents sudden cardiac death in at-risk patients who are not candidates for an implantable defibrillator. The safety and efficacy of the WCD may be impacted by inappropriate shocks (IAS).

Objective: The purpose of this study was to assess the causes and clinical consequences of WCD IAS in survivors of IAS events.

Methods: The Food and Drug Administration's Manufacturers and User Facility Device Experience database was searched for IAS adverse events (AE) that were reported during 2021 and 2022.

Results: A total of 2568 IAS-AE were found (average number of IAS per event: 1.5 ± 1.9; range 1-48). IAS were caused by tachycardias (1255 [48.9%]), motion artifacts (840 [32.7%]), and oversensing (OS) of low-level electrical signals (473 [18.4%]) (P <.001). Tachycardias included atrial fibrillation (AF) (828 [32.2%]), supraventricular tachycardia (SVT) (333 [13.0%]), and nonsustained ventricular tachycardia/fibrillation (NSVT/VF) (87 [3.4%]). Activities responsible for motion-induced IAS included riding a motorcycle, lawnmower, or tractor (n = 128). In 19 patients, IAS induced sustained ventricular tachycardia or ventricular fibrillation that subsequently were terminated by appropriate WCD shocks. Thirty patients fell and suffered physical injuries. Conscious patients (n = 1905) did not use the response buttons to abort shocks (47.9%) or used them improperly (20.2%). IAS resulted in 1190 emergency room visits or hospitalizations, and 17.3% of patients (421/2440) discontinued the WCD after experiencing IAS, especially multiple IAS.

Conclusions: The LifeVest WCD may deliver IAS caused by AF, SVT, NSVT/VF, motion artifacts, and oversensing of electrical signals. These shocks may be arrhythmogenic, result in injuries, precipitate WCD discontinuation, and consume medical resources. Improved WCD sensing, rhythm discrimination, and methods to abort IAS are needed.