Changes in Drug Utilization and Outcome With Cardiac Resynchronization Therapy: A MADIT-CRT Substudy

Background This study sought to assess the association between medication utilization, outcome, and the efficacy of resynchronization therapy in the MADIT-CRT study. Methods and Results Medication use by patients in the MADIT-CRT study was analyzed. Time-dependent Cox proportional hazard regression analyses were performed to assess differences in hospitalization for heart failure (HF) or death. The greater the efficacy of cardiac resynchronization therapy (CRT) as measured by reduction in left ventricular end-systolic volume (LVESV) and increase in left ventricular ejection fraction (LVEF) between baseline and 1 year of follow-up, the greater the likelihood that patients remained on an angiotensin-converting enzyme inhibitor (ACE-I) or angiotensin receptor blocker (ARB) and avoided use of or reduced treatment with diuretics. Treatment with diuretics was associated with a significantly increased risk of HF hospitalization or death (hazard ratio [HR] 1.87, 95% confidence interval [CI] 1.45-2.41; P <.001). In contrast, treatment with an ACE-I/ARB was associated with a significantly decreased risk of HF hospitalization or death (HR 0.58, 95% CI 0.42-0.80; P =.001). Conclusions In HF patients in New York Heart Association functional classes I and II and with wide QRS complexes, efficacy of CRT as measured by improvement in LVESV and LVEF was associated with an increased likelihood of remaining on an ACE-I/ARB and discontinuing diuretic therapy. Discontinuation of diuretics was reflective of improved hemodynamic response to CRT.