Predictors and Risk of Ventricular Tachyarrhythmias or Death in BlackandWhite Cardiac Patients: A MADIT-CRT Trial Substudy.

Abstract

The study sought to analyze the risk of ventricular tachyarrhythmia (VTA) or death in black and whitesubjects implanted with implantable cardioverter-defibrillators (ICDs) or defibrillator and combined cardiac resynchronization therapy (CRT-D) in the MADIT-CRT (Multicenter Automatic Defibrillator Implantation with Cardiac Resynchronization Therapy) trial. There are limited data on ethnic differences in the risk for VTA in mildly symptomatic heart failure patients with left ventricular dysfunction. The risk for first VTA (≥180 beats/min) or death was evaluated in black (n= 139) versus white (n= 1,638) patients enrolled in the MADIT-CRT trial using Kaplan-Meier survival analyses and Cox proportional hazards regression models after adjustment for relevant clinical covariates. Multivariate analysis was used to identify race-specific risk factors for VTA. At 4 years of follow-up, the cumulative probability for a first VTA or death was significantly higher among black patients (42%) as compared with whites (34%; log-rank p value for the overall difference during follow-up= 0.01). Multivariate analysis confirmed significantly higher risk of VTA or death (hazard ratio: 1.60; 95% confidence interval: 1.18 to 2.17; p= 0.002), and higher risk of VTA alone (hazard ratio: 1.71; 95% confidence interval: 1.22 to 2.41; p= 0.002) in blacks compared to whites. The findings were similar in both ICD and CRT-D implanted patients, with no significant race-to-treatment-interaction (interaction p values >0.05). Independent risk factors for VTA among blacks included increased systolic blood pressure values and larger cardiac volumes. In the MADIT-CRT trial, black patients had a significantly higher rate of ventricular tachyarrhythmias or death compared to whites, with either an implanted ICD or CRT-D. (MADIT-CRT: Multicenter Automatic Defibrillator Implantation with Cardiac Resynchronization Therapy [MADIT-CRT], NCT00180271; Multicenter Automatic Defibrillator Implantation with Cardiac Resynchronization Therapy Post Approval Registry [MADIT-CRT PAR], NCT01294449; MADIT-CRT LONG-TERM INTERNATIONAL FOLLOW-UP REGISTRY-EUROPE, NCT02060110).