Why the study?
Does cardiac resynchronization therapy (CRT) improve outcomes in heart failure patients with narrow QRS duration (<130 ms) depending on left ventricular size?
Does cardiac resynchronization therapy (CRT) improve outcomes in heart failure patients with narrow QRS duration (<130 ms) depending on left ventricular size?
In heart failure patients with narrow QRS duration, CRT may worsen outcomes in those with larger left ventricles but could be beneficial in those with smaller left ventricles relative to QRS duration.
Caution against CRT in narrow-QRS HF with larger LVEDV; extends selection criteria research via QRSd/LVEDV interaction.
Background Longer QRS duration ( QRS d) improves, but increased left ventricular ( LV ) end‐diastolic volume ( LVEDV ) reduces, efficacy of cardiac resynchronization therapy ( CRT ). QRS d/ LVEDV ratios differ between sexes. We hypothesized that in the Echo CRT (Echocardiography Guided Cardiac Resynchronization Therapy) trial enrolling patients with heart failure with QRS d <130 ms, those with larger LVEDV would deteriorate but those with the highest QRS d/ LVEDV would improve with CRT . Methods and Results Primary outcome in patients (n=787, 72% men, 93% New York Heart Association class III , QRS d <130 ms, LV ejection fraction ≤35%, LV dilation and dyssynchrony) randomized to CRT ‐ ON or CRT‐ OFF and followed up for 19 months was compared according to LVEDV (height indexed) or QRS d/ LVEDV ratio, in multivariable analysis. Structural remodeling was assessed echocardiographically 6 months after implantation. Patients with baseline LVEDV higher than or equal to median worsened with CRT (death/heart failure hospitalization: CRT ‐ ON versus CRT ‐ OFF , 35.2% versus 24.5% [hazard ratio, 1.64; 95% confidence interval, 1.11–2.42; P =0.012]), but those with LVEDV lower than median remained unaffected. Patients with the highest QRS d/ LVEDV ratio improved with CRT (death/heart failure hospitalization in top quartile: 20.9% in CRT‐ ON [n=91] versus 28.3% in CRT‐OFF [n=106] [hazard ratio, 0.64; 95% confidence interval, 0.34–1.24; P =0.188], versus the remaining quartiles: 31.7% in CRT‐ON [n=300] versus 24.8% in CRT‐OFF [n=290] [hazard ratio, 1.47; 95% confidence interval, 1.07–2.02; P =0.016], test for interaction P =0.046). QRS d and dyssynchrony were similar between groups. The 3‐way test for interaction indicated no sex‐specific effects. However, numerically, men with LVEDV higher than or equal to median accounted for worse outcomes of CRT ‐ ON . Women, with the highest QRS d/ LVEDV ratio exhibited significant reverse remodeling. Conclusion CRT has opposite effects among patients with heart failure with QRS d <130 ms according to LV size: worsening outcomes in patients with larger LV, but inducing beneficial effects in those with smaller LV . Clinical Trial Registration URL: https://www.clinicaltrials.gov/ . Unique identifier: NCT 00683696.
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Varma et al. (2018) studied this question.
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