Association Between a Prolonged PR Interval and Outcomes of Cardiac Resynchronization Therapy

Background: A prolonged PR interval is common among cardiac resynchronization therapy (CRT) candidates; however, the association between PR interval and outcomes is unclear, and the data are conflicting. Methods: We conducted inverse probability weighted analyses of 26 451 CRT-eligible (ejection fraction ≤35, QRS ≥120 ms) patients from the National Cardiovascular Data Registry ICD Registry to assess the association between a prolonged PR interval (≥230 ms), receipt of CRT with defibrillator (CRT-D) versus implantable cardioverter defibrillator (ICD), and outcomes. We first tested the association between a prolonged PR interval and outcomes among patients stratified by device type. Next, we performed a comparative effectiveness analysis of CRT-D versus ICD among patients when stratified by PR interval. Using Medicare claims data, we followed up with patients up to 5 years for incident heart failure hospitalization or death. Results: Patients with a PR≥230 ms (15%; n=4035) were older and had more comorbidities, including coronary artery disease, atrial arrhythmias, diabetes mellitus, and chronic kidney disease. After risk adjustment, a PR≥230 ms (versus PR<230 ms) was associated with increased risk of heart failure hospitalization or death among CRT-D (hazard ratio, 1.23; 95% confidence interval, 1.14–1.31;P <0.001) but not ICD recipients (hazard ratio, 1.08; 95% confidence interval, 0.97–1.20;P =0.17) (P interaction =0.043). CRT-D (versus ICD) was associated with lower rates of heart failure hospitalization or death among patients with PR<230 ms (hazard ratio, 0.79; 95% confidence interval, 0.73–0.85;P <0.001) but not PR≥230 ms (hazard ratio, 1.01; 95% confidence interval, 0.87–1.17;P =0.90) (P interaction =0.0025).Conclusions: A PR≥230 ms is associated with increased rates of heart failure hospitalization or death among CRT-D patients. The real-world comparative effectiveness of CRT-D (versus ICD) is significantly less among patients with a PR≥230 ms in comparison with patients with a PR<230 ms.