The Impact of the PR Interval in Patients Receiving Cardiac Resynchronization Therapy

Objectives This study sought to evaluate the impact of baseline PR interval on cardiac resynchronization therapy (CRT) outcomes in the REVERSE (Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction) study. Background The baseline electrocardiogram has important prognostic value to determine response to CRT. Specifically, QRS duration and morphology are strong predictors of response and outcomes; however, the prognostic importance of the PR interval is less clear. Methods REVERSE was a double-blinded, randomized study of CRT in mild heart failure (HF). The primary endpoint was the analysis of patients in sinus rhythm (n = 582) of the time-to–first HF hospitalization or death during the 2-year randomized period of the trial. In addition, the long-term impact of PR interval was assessed in the cohort actively on CRT during the pre-planned 5-year follow-up. Subjects were analyzed by PR interval, grouped by the median (180 ms) in 20-ms bins or as a continuous variable depending on the analysis performed. Secondary endpoints included the clinical composite score and echocardiographic measures of reverse remodeling. Results During the randomized phase of the study, CRT had similar effectiveness for both PR 180 ms (HR: 0.57) subgroups (interaction p = 0.33). Similar results were observed when PR interval was grouped in 20-ms bins or treated as a continuous variable. In multivariable analysis of the long-term follow-up, left bundle branch block morphology, New York Heart Association functional class, HF etiology, and QRS duration, but not PR interval, predicted HF hospitalization or death. Conclusions Baseline PR interval does not affect clinical outcomes or reverse remodeling with CRT in mild HF. (Resynchronization Reverses Remodeling in Systolic Left Ventricular Dysfunction [REVERSE]; NCT00271154)