Outcomes during and after the use of the wearable cardioverter-defibrillator in a tertiary-care and a regional hospital in Switzerland

INTRODUCTION: The wearable cardioverter-defibrillator (WCD) has established itself in treatment of potentially life-threatening ventricular arrhythmias, when implantation of an implantable cardioverter-defibrillator (ICD) is not warranted. Careful patient selection for this therapy is crucial, but unfortunately very little information from randomised controlled trials is available to guide clinical decision-making. Consequently, data from real-world patient registries play a more important role in this context. MATERIALS AND METHODS: A retrospective observational study was conducted at the University Hospital of Zurich and the GZO Regional Healthcare Centre in Wetzikon. Clinical databases were screened for patients with a history of WCD use from the time of its approval in Switzerland in July 2014 until February 2018. Baseline characteristics, WCD data and outcome data, with an emphasis on ICD implantation and ICD therapies, were collected and analysed. RESULTS: Two-hundred and seven patients were included in the primary analysis. Eighty-six percent were male and the mean age was 58 ± 13 years. The underlying heart disease was ischaemic cardiomyopathy (ICM), non-ischaemic cardiomyopathy (NICM) and congenital/inherited heart diseases in 60, 35 and 5%, respectively. The most common indication for WCD use was heart failure with an ejection fraction (EF) <35% due to ICM or NICM (43 and 27%, respectively). Three of the 207 patients received an appropriate shock over a median WCD wear-time of 62 days (interquartile range [IQR] 35–95). No inappropriate shocks were registered. Median average daily wear-time was 22.6 hours (IQR 19.9–23.2) and was significantly shorter for patients for whom WCD discontinuation was due to comfort issues (17 patients, p = 0.003). After the end of WCD therapy, 48% were implanted with an ICD. In those receiving an ICD, the rate of appropriate ICD therapies (either shock or antitachycardia pacing) was 8% during a median follow-up of 110 days (IQR 23–421). CONCLUSION: The WCD is safe and effective in terminating malignant ventricular arrhythmias. A substantial subgroup of patients, however, discontinued WCD use prematurely because of comfort issues. This subset of patients deserves further attention in clinical practice to ensure therapy adherence. .