Abstract 16542: Cardiac Resynchronization Therapy Decreases the Risk of Ventricular Tachyarrhythmias in the MADIT-CRT Trial
Background: This study aimed to determine whether resynchronization therapy alters the risk of ventricular tachyarrhythmias in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial — Cardiac Resynchronization Therapy (MADIT-CRT) trial.
Methods: MADIT-CRT enrolled ischemic NYHA class I or II and nonischemic NYHA class II cardiomyopathy patients with ejection fraction <=30% and QRS duration =>130 ms. All arrhythmia episodes for which therapy was delivered were blindly adjudicated. The occurrence of ventricular tachycardia (VT), ventricular fibrillation (VF), and cardiac death (CD) were compared in the implantable cardioverter defibrillator (ICD) arm and the resynchronization with defibrillator (CRT-D) arm of the trial.
Results: Among 1,820 patients in the trial, 366 (20%) had one or more VT or VF episodes for which ICD shock or anti-tachycardia (ATP) therapy was delivered. Combined endpoint of VT or VF or CD was experienced by 416 (23%) patients. The patients having VT or VF episodes were less likely to have LBBB at baseline, more likely to be younger, to have had a prior MI, a lower baseline EF and a narrower QRS compared to patients without VT or VF episodes. In addition, occurrence of interim time-dependent VT/VF was predictive of both death (HR=2.34, p<0.001) and HF/Death (HR=2.02, p<0.001). The Figure shows the cumulative probability of VT/VF/CD by treatment arm indicating significant reduction in the risk of this combined endpoint by CRT-D. When adjusting for LBBB, age, gender, QRS, and ischemic status, CRT-D reduced the risk of VT/VF (HR=0.78, p=0.021) and VT/VF/CD (HR=0.80, p=0.021).
Conclusions: Heart failure patients with NYHA class I or II and ejection fraction ≤30% who receive CRT-D are at a lower risk for the occurrence of VT or VF than those treated with ICD only.
- © 2010 by American Heart Association, Inc.