Ventricular arrhythmias in patients with newly diagnosed nonischemic cardiomyopathy: Insights from the PROLONG study.

Background: Patients with nonischemic cardiomyopathy (NICM) reportedly have low incidence of appropriate shocks from wearable cardioverter-defibrillators (WCDs). A recent study questions the benefit from primary preventive implantation of implantable cardioverter-defibrillators in NICM. We therefore analyzed a subgroup of patients with NICM from the PROLONG study.

Hypothesis: Patients with newly diagnosed NICM show a risk for ventricular tachyarrhythmia.

Methods: The PROLONG study included 167 patients with newly diagnosed heart failure and left ventricular ejection fraction (LVEF) ≤35% with a WCD. Patients with NICM were identified and included in this analysis.

Results: 117 patients presented with NICM. Sixty-five (55%) were male; mean age was 51 ± 15 years. Mean LVEF at diagnosis was 23% ± 7%. Mean follow-up was 11 ± 10 months. Mean WCD wear time was 101 ± 82 days; mean wear time per day was 21.4 ± 4.5 hours. Overall, 12 ventricular arrhythmias occurred in 10 (9%) patients (6 DCM, 4 PPCM). Nine appropriate WCD shocks for hemodynamically unstable ventricular tachycardia/fibrillation in 8 (7%) patients were observed. Two patients presented sustained hemodynamically stable ventricular tachycardia for >30 minutes detected by the WCD, but withheld WCD therapy.

Conclusions: Patients with newly diagnosed NICM and LVEF ≤35% show an elevated risk of ventricular tachycardia/fibrillation during initiation and optimization of heart failure therapy. To prevent sudden cardiac death, WCD should be considered in patients with newly diagnosed NICM with severely reduced LVEF.