title: The effect of cardiac resynchronization on morbidity and mortality in heart failure.
abstract: BACKGROUND
  Cardiac resynchronization reduces symptoms and improves left ventricular function in many patients with heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony. We evaluated its effects on morbidity and mortality.
  
  
  METHODS
  Patients with New York Heart Association class III or IV heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony who were receiving standard pharmacologic therapy were randomly assigned to receive medical therapy alone or with cardiac resynchronization. The primary end point was the time to death from any cause or an unplanned hospitalization for a major cardiovascular event. The principal secondary end point was death from any cause.
  
  
  RESULTS
  A total of 813 patients were enrolled and followed for a mean of 29.4 months. The primary end point was reached by 159 patients in the cardiac-resynchronization group, as compared with 224 patients in the medical-therapy group (39 percent vs. 55 percent; hazard ratio, 0.63; 95 percent confidence interval, 0.51 to 0.77; P<0.001). There were 82 deaths in the cardiac-resynchronization group, as compared with 120 in the medical-therapy group (20 percent vs. 30 percent; hazard ratio 0.64; 95 percent confidence interval, 0.48 to 0.85; P<0.002). As compared with medical therapy, cardiac resynchronization reduced the interventricular mechanical delay, the end-systolic volume index, and the area of the mitral regurgitant jet; increased the left ventricular ejection fraction; and improved symptoms and the quality of life (P<0.01 for all comparisons).
  
  
  CONCLUSIONS
  In patients with heart failure and cardiac dyssynchrony, cardiac resynchronization improves symptoms and the quality of life and reduces complications and the risk of death. These benefits are in addition to those afforded by standard pharmacologic therapy. The implantation of a cardiac-resynchronization device should routinely be considered in such patients.
authors.affiliation: Department of Cardiology, Castle Hill Hospital, Kingston-upon-Hull, United Kingdom. j.g.cleland@hull.ac.uk
authors.forename: John G F
authors.initials: JG
authors.lastname: Cleland
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Daubert
authors.forename: Erland
authors.initials: E
authors.lastname: Erdmann
authors.forename: Nick
authors.initials: N
authors.lastname: Freemantle
authors.forename: Daniel
authors.initials: D
authors.lastname: Gras
authors.forename: Lukas
authors.initials: L
authors.lastname: Kappenberger
authors.forename: Luigi
authors.initials: L
authors.lastname: Tavazzi
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D010138:Pacemaker, Artificial / Q000009:adverse effects; D013318:Stroke Volume; D016019:Survival Analysis; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000628:therapy