Abstract
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.
Highlights
Cardiac resynchronization therapy (CRT) is recommended for patients with mild-to-moderate heart failure (HF), reduced ejection fraction (EF), and ventricular electrical dyssynchrony as demonstrated by prolonged QRS duration.[1,2] As with most therapies, individual patient response traditionally evaluated after 6 months of CRT varies, with up to one-third of those treated categorized as nonresponders.[3]
The included studies had similar inclusion/exclusion criteria. These consisted of New York Heart Association (NYHA) functional class III or IV, left ventricular EF 35%, and QRS duration 130 ms (.120 ms for Adaptive CRT) while on guideline-directed medical therapy
There were 1603 patients assigned to CRT therapy included in the response assessment who were followed up for a mean of 14.8 months
Summary
Cardiac resynchronization therapy (CRT) is recommended for patients with mild-to-moderate heart failure (HF), reduced ejection fraction (EF), and ventricular electrical dyssynchrony as demonstrated by prolonged QRS duration.[1,2] As with most therapies, individual patient response traditionally evaluated after 6 months of CRT varies, with up to one-third of those treated categorized as nonresponders.[3] This has traditionally encompassed all patients who do not realize full benefit, including both patients who progress (or worsen) and those who neither improve nor worsen (remain stabilized). When response was defined using the clinical composite score (CCS)[4] to measure clinical response at 6 months, 31% were categorized as not improved (“unchanged” or “worsened”).[5] If structural reverse remodeling cardiac effects, such as left ventricular end-systolic volume index (LVESVi) are considered, the percentage of patients may be higher. Cardiac resynchronization therapy (CRT) reduces mortality and improves outcomes in appropriately selected patients with heart failure (HF); response may vary
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