Ventricular Tachycardia Predicts All-Cause Mortality and Nonsudden Cardiac Death in Nonischemic Cardiomyopathy

BACKGROUND: Patients with nonischemic cardiomyopathies (NICMs) are at a risk for end-stage heart failure and death from ventricular arrhythmias. Implanted defibrillators (ICDs) protect against sudden arrhythmic death, but several studies suggest that ventricular arrhythmias are associated with worse outcomes despite ICDs. OBJECTIVES: This study evaluated the relationship of ventricular tachycardia (VT) with total mortality and nonsudden cardiovascular death (NSCVD) in NICM patients with ICDs enrolled in 2 multicentre trials. METHODS: Patient-level data were analyzed from 2 prospective trials: DANISH (Danish Trial to Assess the Efficacy of ICDs in Patients with Nonischemic Systolic Heart Failure on Mortality) (ICD for primary prevention of sudden death) and dilated cardiomyopathy-VT (VT ablation). Primary endpoints were all-cause mortality or heart transplantation, and the secondary endpoint was NSCVD. Analyses included the entire group with multivariable analysis, a propensity-matched subgroup with and without VT at entry, VT patients with recent-onset VT in dilated cardiomyopathy-VT, and DANISH patients experiencing VT after primary prevention ICD. RESULTS: Among 828 patients (median age 64 years, 23.3% females, median left-ventricular ejection fraction of 36%), 148 deaths occurred during a median follow-up of 3.9 years, with 78 (53%) due to NSCVD. Despite younger age and better left-ventricular ejection fraction, VT was independently associated with a >4-fold increase in mortality or transplantation (adjusted HR: 4.27 [95% CI: 2.60-7.03]) and a 7-fold increase in NSCVD (adjusted HR: 7.28 [95% CI: 3.80-13.97]). The findings were consistent across all subgroups. CONCLUSIONS: Patients with NICM experiencing VT are at an increased risk for mortality and NSCVD, suggesting that VT can be a marker for a more severe cardiomyopathy with important clinical implications.