The importance of early evaluation after cardiac resynchronization therapy to redefine response: Pooled individual patient analysis from 5 prospective studies

Abstract

BackgroundCardiac resynchronization therapy (CRT) reduces mortality and improves outcomes in appropriately selected patients with heart failure (HF); however, response may vary.ObjectiveWe sought to correlate 6-month CRT response assessed by clinical composite score (CCS) and left ventricular end-systolic volume index (LVESVi) with longer-term mortality and HF-related hospitalizations.MethodsIndividual patient data from 5 prospective CRT studies—Multicenter InSync Randomized Clinical Evaluation (MIRACLE), Multicenter InSync ICD Randomized Clinical Evaluation (MIRACLE ICD), InSync III Marquis, predictors of response to cardiac resynchronization therapy (PROSPECT), and Adaptive CRT—were pooled. Classification of CRT response status using CCS and LVESVi were made at 6 months. Kaplan-Meier analyses were used to assess time to mortality. Cox proportional hazards regression models were used to compute hazard ratios (HRs) for the 3 levels of CRT response: improved, stabilized, and worsened. Adjusted models controlled for baseline factors known to influence both CRT response and mortality. HF-related hospitalization was compared between CRT response categories using incidence rate ratios.ResultsAmong a total of 1603 patients, 1426 and 1165 were evaluated in the CCS and LVESVi outcome assessments, respectively. Mortality was significantly lower for patients in the improved (CCS: HR 0.22; 95% confidence interval [CI] 0.15–0.31; LVESVi: HR 0.40; 95% CI 0.27–0.60) and stabilized (CCS: HR 0.38; 95% CI 0.24–0.61; LVESVi: HR 0.41; 95% CI 0.25–0.68) groups than in the worsened group for both measures after adjusting for potential confounders.ConclusionPatients with a worsened CRT response status have a high mortality rate and HF-related hospitalizations. Stabilized patients have a more favorable prognosis than do worsened patients and thus should not be considered CRT nonresponders. Cardiac resynchronization therapy (CRT) reduces mortality and improves outcomes in appropriately selected patients with heart failure (HF); however, response may vary. We sought to correlate 6-month CRT response assessed by clinical composite score (CCS) and left ventricular end-systolic volume index (LVESVi) with longer-term mortality and HF-related hospitalizations. Individual patient data from 5 prospective CRT studies—Multicenter InSync Randomized Clinical Evaluation (MIRACLE), Multicenter InSync ICD Randomized Clinical Evaluation (MIRACLE ICD), InSync III Marquis, predictors of response to cardiac resynchronization therapy (PROSPECT), and Adaptive CRT—were pooled. Classification of CRT response status using CCS and LVESVi were made at 6 months. Kaplan-Meier analyses were used to assess time to mortality. Cox proportional hazards regression models were used to compute hazard ratios (HRs) for the 3 levels of CRT response: improved, stabilized, and worsened. Adjusted models controlled for baseline factors known to influence both CRT response and mortality. HF-related hospitalization was compared between CRT response categories using incidence rate ratios. Among a total of 1603 patients, 1426 and 1165 were evaluated in the CCS and LVESVi outcome assessments, respectively. Mortality was significantly lower for patients in the improved (CCS: HR 0.22; 95% confidence interval [CI] 0.15–0.31; LVESVi: HR 0.40; 95% CI 0.27–0.60) and stabilized (CCS: HR 0.38; 95% CI 0.24–0.61; LVESVi: HR 0.41; 95% CI 0.25–0.68) groups than in the worsened group for both measures after adjusting for potential confounders. Patients with a worsened CRT response status have a high mortality rate and HF-related hospitalizations. Stabilized patients have a more favorable prognosis than do worsened patients and thus should not be considered CRT nonresponders.

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