title: Assessing mitral regurgitation in the prediction of clinical outcome after cardiac resynchronization therapy.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) has been shown to reduce mitral regurgitation (MR), although the clinical impact of this improvement remains uncertain.
  
  
  OBJECTIVE
  We sought to evaluate the impact of MR improvement on clinical outcome after CRT and to assess predictors and mechanism for change in MR.
  
  
  METHODS
  This was a cohort study of patients undergoing CRT for conventional indications with baseline and follow-up echocardiography (at 6 months). MR severity was classified into 4 grades. The primary end point was time to all-cause death or time to first heart failure (HF) hospitalization assessed at 3 years.
  
  
  RESULTS
  A total of 439 patients were included: median age was 70.2 years, 90 (20.5%) were women, 255 (58.1%) with ischemic cardiomyopathy, and mean QRS width was 162 ms. Worsening severity of baseline MR was independently predictive of HF or all-cause mortality (hazard ratio 1.33; 95% confidence interval 1.01-1.75; P = .042). Reduction in MR after CRT was significantly associated with lower HF hospitalization and improved survival (hazard ratio 0.65; 95% confidence interval 0.49-0.85; P = .002). Degree of baseline MR and longer surface QRS to left ventricular lead time were significant predictors of MR change. Patients with MR reduction exhibited lower mitral valve tenting area (P < .001) and coaptation height (P < .001) than those with stable or worsening MR, suggestive of improved ventricular geometry as a mechanism for change in MR.
  
  
  CONCLUSIONS
  Degree of baseline MR and change in MR after CRT predicted all-cause mortality and HF hospitalization at 3 years. Longer surface QRS to left ventricular lead time at implant may be a means to target MR improvement.
authors.affiliation: Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts; Heart Rhythm Center, Section of Cardiology, University of Chicago, Chicago, Illinois.
authors.forename: Gaurav A
authors.initials: GA
authors.lastname: Upadhyay
authors.affiliation: Cardiology Division.
authors.forename: Neal A
authors.initials: NA
authors.lastname: Chatterjee
authors.affiliation: Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Jagdesh
authors.initials: J
authors.lastname: Kandala
authors.affiliation: Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Friedman
authors.affiliation: Echocardiography Laboratory of the Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Mi-Young
authors.initials: MY
authors.lastname: Park
authors.affiliation: Cardiology Division.
authors.forename: Sara R
authors.initials: SR
authors.lastname: Tabtabai
authors.affiliation: Echocardiography Laboratory of the Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Judy
authors.initials: J
authors.lastname: Hung
authors.affiliation: Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts. Electronic address: jsingh@partners.org.
authors.forename: Jagmeet P
authors.initials: JP
authors.lastname: Singh
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy; D009202:Cardiomyopathies / Q000628:therapy; D015331:Cohort Studies; D004452:Echocardiography; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000175:diagnosis* / Q000517:prevention & control; D016896:Treatment Outcome
keywords: Biventricular pacing; Cardiac resynchronization therapy (CRT); Heart failure; LV lead electrical delay; Mitral regurgitation; QLV