Appropriateness of Prescription and Safety of Wearable Cardioverter Defibrillators: A Single-center Experience

Introduction Wearable cardioverter defibrillators (WCD) are recommended for patients with a high risk of sudden cardiac death (SCD) secondary to arrhythmia that have not qualified for placement of an implantable cardiac defibrillator (ICD). This study provides insights into a single-center experience with WCD in terms of its usage and safety. Materials and methods We studied all patients that were prescribed a WCD in the Fairview Hospital in Cleveland Clinic Health System, from January 2014 to June 2016. Institutional Review Board of the Cleveland Clinic approved the study. A retrospective chart review was performed to collect data regarding demographics and baseline comorbidities including age, gender, history of hypertension, diabetes, coronary artery disease, and chronic kidney disease. The patients that were lost to follow up in our electronic medical record (EMR) were excluded. Ejection fraction (EF) at the time of diagnosis and follow-up was recorded. The primary outcome was ICD placement at follow up focusing on appropriate use while the secondary outcome was delivery of shock (appropriate or inappropriate) focusing on efficacy and safety of the device. Patients were stratified based on ICD placement. Statistical Package for the Social Sciences (SPSS), version 23 (IBM Corp., NY, USA) was used for the statistical analysis. Results We identified 73 patients with WCD placement. After the exclusion of 23/73 (31.5%) patients due to loss of follow-up, 50 patients were included in the study (n=50). Clinical characteristics showed 66% patients were males, 76% had hypertension, 40% had diabetes, 34% had chronic kidney disease, 56% patient had a New York Heart Association functional status of >II and 34% were on anti-arrhythmic medication. Indication for WCD use was ischemic cardiomyopathy in 23/50 (46%) patients and non-ischemic cardiomyopathy in 27/50 (54%) patients. No ICD was placed in 39/50 (78%) patients and ICD was placed in 11/50 (22%) patients at end time of follow up. Mean age was 59.9 years (95% confidence interval (CI), 55.9 - 63.9 years) in the group with no ICD placement and 63.5 years (95% CI, 56.5 - 70.6 years) in the group with ICD placement. Mean EF in the group with no ICD placement at the time of diagnosis was 25.8% (95% CI, 23.8% - 27.9%) which improved by 18.8% to a mean EF of 44.6% (41.1% - 48.1%) at the follow-up. Mean EF in the group with ICD placement was 32.7% (95% CI, 27.6% - 37.9%) which reduced by 4.1% to mean EF of 28.6% (95% CI, 12.2% - 44.9%) which was statistically significant (p<0.0001). Patients who had no ICD placement were followed for an average of 162 days and with ICD placement for 78 days. There was no difference between ischemic or nonischemic groups in getting the ICD. There were no shocks delivered whether appropriate or inappropriate in our population. Conclusion Almost a quarter of the patients that were prescribed WCD in our center ended up with an implanted device which demonstrates appropriate use. Equally important was the observed safety of WCDs as a treatment modality with no inappropriate shocks recorded in the followed cohort.