title: Association Between a Prolonged PR Interval and Outcomes of Cardiac Resynchronization Therapy: A Report From the National Cardiovascular Data Registry.
abstract: 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) (Pinteraction=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) (Pinteraction=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.
authors.affiliation: From Division of Cardiology, Duke University Hospital, Durham, NC (D.J.F., J.P.D., S.M.A.-K.); Duke Clinical Research Institute, Durham, NC (D.J.F., S.M.A.-K.); and Yale University School of Medicine, New Haven, CT (H.B., E.S.S., J.P.C.). daniel.friedman@duke.edu.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Friedman
authors.affiliation: From Division of Cardiology, Duke University Hospital, Durham, NC (D.J.F., J.P.D., S.M.A.-K.); Duke Clinical Research Institute, Durham, NC (D.J.F., S.M.A.-K.); and Yale University School of Medicine, New Haven, CT (H.B., E.S.S., J.P.C.).
authors.forename: Haikun
authors.initials: H
authors.lastname: Bao
authors.affiliation: From Division of Cardiology, Duke University Hospital, Durham, NC (D.J.F., J.P.D., S.M.A.-K.); Duke Clinical Research Institute, Durham, NC (D.J.F., S.M.A.-K.); and Yale University School of Medicine, New Haven, CT (H.B., E.S.S., J.P.C.).
authors.forename: Erica S
authors.initials: ES
authors.lastname: Spatz
authors.affiliation: From Division of Cardiology, Duke University Hospital, Durham, NC (D.J.F., J.P.D., S.M.A.-K.); Duke Clinical Research Institute, Durham, NC (D.J.F., S.M.A.-K.); and Yale University School of Medicine, New Haven, CT (H.B., E.S.S., J.P.C.).
authors.forename: Jeptha P
authors.initials: JP
authors.lastname: Curtis
authors.affiliation: From Division of Cardiology, Duke University Hospital, Durham, NC (D.J.F., J.P.D., S.M.A.-K.); Duke Clinical Research Institute, Durham, NC (D.J.F., S.M.A.-K.); and Yale University School of Medicine, New Haven, CT (H.B., E.S.S., J.P.C.).
authors.forename: James P
authors.initials: JP
authors.lastname: Daubert
authors.affiliation: From Division of Cardiology, Duke University Hospital, Durham, NC (D.J.F., J.P.D., S.M.A.-K.); Duke Clinical Research Institute, Durham, NC (D.J.F., S.M.A.-K.); and Yale University School of Medicine, New Haven, CT (H.B., E.S.S., J.P.C.).
authors.forename: Sana M
authors.initials: SM
authors.lastname: Al-Khatib
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008297:Male; D012042:Registries; D012107:Research Design; D016896:Treatment Outcome
keywords: atrioventricular block; cardiac resynchronization therapy; cardiomyopathies; defibrillators; pacemaker, artificial