Association Between a Prolonged PR Interval and Outcomes of Cardiac Resynchronization Therapy A Report From the National Cardiovascular Data Registry

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.