Abstract 8727: Baseline Functional Status and the Benefit of Cardiac Resynchronization Therapy in Patients with Mildly Symptomatic Heart failure Enrolled in MADIT-CRT
Background: The MADIT-CRT trial showed that cardiac resynchronization therapy with a defibrillator (CRT-D) is associated with a significant reduction in the risk of heart failure (HF) or death in mildly symptomatic patients with left ventricular dysfunction. The aim of the present study was to relate the clinical benefit of CRT-D therapy to baseline functional status, as determined by the 6 minute walk test (6MWT), and to assess the effect of the device on functional status at 1-year in the MADIT-CRT population.
Methods: Multivariate Cox proportional hazards regression modeling was used to assess the effect of CRT-D vs. defibrillator-only therapy on the risk of HF or death and the separate occurrence of all-cause mortality by baseline functional status (dichotomized at the median value of the baseline 6MWT [350 m]) among 1765 patients enrolled in MADIT-CRT.
Results: A lower functional status (6MWT <350m) was associated with a 73% (p < 0.001) increase in the risk of HF or death and a 2.4-fold increase in all-cause mortality among patients treated with defibrillator-only therapy. After multivariate adjustment for relevant covariates CRT-D therapy was associated with a significant 48% (p=0.01) reduction in the risk of all-cause mortality among study patients with a lower functional status who had LBBB at enrollment (Fig.1A), whereas treatment with the device was not associated with a significant survival benefit among study patients with a higher function status (6MWT ≥350m) with LBBB (Fig. 1B). At 1-year of follow-up, improvement in 6MWT was observed in a similar proportion of CRT-D patients (50.2%) and defibrillator-only patients (50.7%) p = 0.84.
Conclusions: A low baseline functional status is a powerful predictor of HF or death among mildly symptomatic HF patients and identifies patients in this population who derive a significant survival benefit from cardiac resynchronization therapy.
- © 2011 by American Heart Association, Inc.