title: Normalization of left ventricular ejection fraction after cardiac resynchronization therapy also normalizes survival.
abstract: BACKGROUND
  Earlier studies in patients with reduced left ventricular ejection fraction (LVEF) ≤35% and prolonged QRS showed better survival outcomes with cardiac resynchronization therapy (CRT). Some patients respond dramatically to CRT by improving their LVEF to the normal range and are considered "super-responders." Our aim was to determine whether super-responders survival increases to levels comparable to the general population. We compared the survival of super-responders to the general population matched for age and sex.
  
  
  METHODS
  Of 909 patients with CRT device implantation between September 1998 and July 2008, 814 patients had pre- and post-CRT echocardiogram. A total of 95 patients with LVEF ≥ 50% following CRT were classified as super-responders. For 92 super-responders, who had U.S. Social Security numbers, an age- and sex-matched example was selected from the Social Security Life Tables. An expected survival plot of the matched population was then compared to the actual survival of super-responders.
  
  
  RESULTS
  Super-responders had comparable survival to the age-sex matched general population (P = 0.53), and Kaplan-Meier survival analysis in 92 patients showed that super-responders with CRT pacemakers had similar survival to those with CRT implantable cardioverter defibrillators (P = 0.77). Super-responders were more likely to be females (54% vs 25%, P < 0.001) and less likely to have significant coronary artery disease (62% vs 42%, P < 0.001).
  
  
  CONCLUSIONS
  Normalization of LVEF by CRT improves survival to levels comparable to the general population. This observation favors the concept that some CRT candidates have a cardiomyopathy likely generated by the conduction abnormality that is reversible through biventricular pacing.
authors.affiliation: Department of Internal Medicine, Cleveland Clinic, Cleveland, Ohio 44195, USA.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Manne
authors.forename: John
authors.initials: J
authors.lastname: Rickard
authors.forename: Niraj
authors.initials: N
authors.lastname: Varma
authors.forename: Mina K
authors.initials: MK
authors.lastname: Chung
authors.forename: Patrick
authors.initials: P
authors.lastname: Tchou
mesh_terms: D017677:Age Distribution; D000368:Aged; D058406:Cardiac Resynchronization Therapy / Q000401:mortality* / Q000706:statistics & numerical data*; D015897:Comorbidity; D005260:Female; D006333:Heart Failure / Q000453:epidemiology* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D009820:Ohio / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D013318:Stroke Volume; D015996:Survival Rate; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000401:mortality* / Q000517:prevention & control*
keywords: biventricular (BiV) pacing devices; cardiac resynchronization therapy; cardiomyopathy; super-responders