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

Abstract

Objectives: The study sought to analyze the risk of ventricular tachyarrhythmia (VTA) or death in black and white subjects 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.

Background: There are limited data on ethnic differences in the risk for VTA in mildly symptomatic heart failure patients with left ventricular dysfunction.

Methods: 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.

Results: 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.

Conclusions: 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).

Keywords: cardiac resynchronization therapy with defibrillator; death; implantable cardioverter-defibrillator; mild heart failure; ventricular tachyarrhythmias.