Abstract 10673: PR-Interval Identifies Clinical Response in Patients With Non-LBBB - A MADIT-CRT Sub-Study
Background: In MADIT-CRT, patients with a non-LBBB (including right bundle branch block or intraventricular conduction delay) did not derive clinical benefit from a cardiac resynchronization therapy implantable cardioverter defibrillator device (CRT-D) compared to an implantable defibrillator (ICD). We hypothesized that the baseline PR-interval modulates clinical response to CRT-D in patients with non-LBBB.
Methods: Non-LBBB patients (n=537, 30%) were divided into two groups by baseline PR-interval: normal (including minimally prolonged) PR (PR < 230 ms), and prolonged PR (PR ≥ 230 ms). The primary end point was heart failure (HF) or death. Secondary end point was all-cause mortality. Cox proportional hazards regression models were used to compare the risk of end points by CRT-D to ICD therapy in the PR subgroups.
Results: There were 96 patients (22%) with a prolonged PR and 438 patients (78%) with a normal PR interval. In non-LBBB patients with a prolonged PR-interval, CRT-D treatment was associated with a 73% reduction in the risk of HF/Death (HR=0.27, 95% CI: 0.13-0.57, p<0.001), and 81% decrease in the risk of all-cause mortality (HR=0.19, 95% CI: 0.13-0.57, p<0.001) compared to ICD therapy. In non-LBBB patients with normal PR, CRT-D therapy was associated with a trend towards an increased risk of HF/Death (HR=1.45, 95% CI: 0.96-2.19, p=0.078, interaction p-value<0.001) (Figure) and more than a 2-fold higher risk for mortality (HR=2.14, 95% CI: 1.12-4.09, p=0.022, interaction p-value<0.001) compared to ICD therapy.
Conclusions: In MADIT-CRT, non-LBBB patients with a prolonged PR-interval derive significant clinical benefit from a CRT-D implantation compared to an ICD alone. In non-LBBB patients with a normal PR-interval CRT-D implantation may be deleterious.
- © 2013 by American Heart Association, Inc.