Risk of recurrent ventricular tachyarrhythmia following the occurrence of a first ventricular arrhythmic event in patients with a primary prevention implantable cardioverter-defibrillator.

Background: There are limited data on clinical and arrhythmic outcomes after a first ventricular tachyarrhythmia (VTA) in heart failure (HF) patients who receive a primary prevention implantable cardioverter-defibrillator (ICD).

Objective: This study was designed to quantify the burden of and to identify risk factors for recurrent VTA in this population and to evaluate the risk of all-cause mortality associated with recurrent VTA.

Methods: The study comprised 789 patients who experienced VTA following primary prevention ICD implantation in 5 ICD trials (MADIT-II, MADIT-RISK, MADIT-CRT, MADIT-RIT, RAID). Landmark analysis was used to quantify the burden and to identify predictors of recurrent VTA. Time-dependent analysis was used to evaluate the association of VTA recurrence with subsequent mortality.

Results: The mean age of the study patients was 63 years, and 17% were women. The cumulative probability of experiencing at least 1 recurrent VTA episode at 3 years after a first VTA episode was 60%; the recurrent VTA burden after a first event during 3 years was 2.8 episodes per patient. The risk of recurrent VTA remained ≥56% at 3 years regardless of baseline clinical and echocardiographic risk factors. VTA recurrence was associated with a significant 2-fold increased risk of subsequent all-cause mortality.

Conclusion: Patients with a primary prevention ICD who experience an episode of VTA are at high risk of recurrent VTA, regardless of baseline risk factors. Recurrent VTA is associated with a pronounced increase in the risk of death. These findings suggest a need for early intervention after a first VTA in patients who receive a primary prevention ICD.