Wearable cardioverter-defibrillator as a bridge to cardiac transplantation: A national database analysis

Background Life-threatening ventricular arrhythmias (VAs) and sudden cardiac death (SCD) are common in patients awaiting heart transplantation (HT), and the implantable cardioverter-defibrillator (ICD) is often used for primary prevention in this setting. Use of ICDs in these patients is not without risks and is sometimes contraindicated. The wearable cardioverter-defibrillator (WCD) may be a reasonable alternative to bridge the period of risk leading up to HT. Methods We obtained a convenience sample of patients prescribed an WCD as a bridge therapy to HT. The available data consisted of demographics, cardiac transplantation status, associated comorbidities, device use, device-stored electrocardiogram (ECG) and reason for discontinuing the WCD. Statistical analyses were performed using SPSS version 17 and GraphPad PRISM 5. Results The registry included 121 patients consisting of 83 (69%) men and 38 (31%) women. The mean age was 44 ± 18 years. Mean ejection fraction was 25 ± 15%. Non-ischemic cardiomyopathy (CMP) was the underlying diagnosis in 67 (55%) patients, whereas 21 (17%) patients had ischemic CMP and 33 (27%) had a mixed or uncharacterized CMP. New York Heart Association Class III heart failure was present in 32% and 34% were in Class IV. Eighty-eight patients (73%) were being evaluated for HT or were on an HT waiting list, and 33 patients (27%) had had a prior HT, experienced rejection, and were awaiting re-transplantation. The patients wore the WCD for an average of 127 ± 392 days (median 39 days) with average daily use of 17 ± 7 hours (median 20 hours). Seven patients (6%) received appropriate WCD shocks. Fifty-one patients (42%) ended use after ICD implantation and 13 patients (11%) after HT. There were 11 deaths (9%). Conclusions A significant proportion of patients on the HT waiting list will have VA. WCD use in our study showed high compliance and efficacy and a low complication rate, suggesting that the WCD is a reasonable bridge therapy for preventing SCD in patients awaiting HT.