Wearable Cardioverter Defibrillators after Cardiopulmonary Bypass Surgery

Objectives: Patients with severely reduced cardiac pump function are at risk to develop ventricular arrhythmias (VAs). Cardiac surgery improves impaired cardiac function after 3 to 6 months in most cases. Patients with cardiac surgery and reduced cardiac function carry an elevated risk for sudden cardiac death which is especially high in the early postoperative period. A possible therapy is the prophylactic use of a wearable cardioverter defibrillator (WCD) vest. This study aimed to analyze the incidence of postoperative VA, cardiac pump function, WCD shocks, and the necessity of permanent ICD implantation in patients who wore a WCD after cardiac surgery with cardiopulmonary bypass.

Methods: In this single-center study, we retrospectively analyzed all patients who were discharged with a WCD and who underwent cardiac surgery with cardiopulmonary bypass between 2012 and 2018. Patients with isolated ICD explantation due to infection were not included. The WCD was prescribed for patients with a left ventricular ejection fraction (LVEF) of ≤35%. The clinical data and echocardiography results were obtained from our institution’s medical records. WCD-wearing time, VA, and WCD shocks were analyzed in the ECGs automatically recorded by the WCD.

Results: A total of 139 patients were included. Mean age was 64 ± 14 years; 116 (83.5%) patients were male. Sixty-seven (48%) had isolated coronary artery bypass graft (CABG) surgeries, 33 (24%) isolated valve surgeries, 29 (21%) combined valve and CABG surgeries, and 10 (7%) other cardiac surgeries. Wearing time was 23.5 hours per day. LVEF was 27.6 ± 6% after surgery and improved to 34.2 ± 12% (p < 0.001) in the follow-up. Fifteen (10.8%) patients experienced VA: three (2%) patients had ventricular fibrillation (VF) and were successfully defibrillated by the WCD. Further 12 (8.6%) patients experienced non-sustained ventricular tachycardias. No patient died while wearing the WCD. A permanent ICD was implanted in 25 (18%) patients after the WCD period.

Conclusion: The adherence of our patients was very high (23.5 hours/d), despite of sternotomy. Cardiac surgery patients with severely reduced pump function were at risk for malignant arrhythmias: 2% were successfully defibrillated for VF, and 10.8% experienced VA. The LVEF significantly improved after cardiac surgery (+6.6%, p < 0.001), and thus, a permanent ICD implantation was often avoided. Only 18% needed a permanent ICD.

No conflict of interest has been declared by the author(s).