title: The effect of bilateral internal thoracic artery grafting on survival during 20 postoperative years.
abstract: BACKGROUND
  To compare survival of patients receiving bilateral internal thoracic artery grafts and single internal thoracic artery grafts more than 20 postoperative years, assess magnitude of benefit, and identify predictors of benefit.
  
  
  METHODS
  From cohorts of 8123 patients receiving single internal thoracic artery grafts and 2001 receiving bilateral internal thoracic artery grafts during primary isolated bypass operations for multivessel coronary disease between 1971 and 1989, we identified 1152 propensity-matched pairs. Mean follow-up of survivors was 16.5 years, with 51 patients followed for 20 years or more. Hazard function methodology was used to identify risk factors for mortality, compare survival, and assess magnitude of benefit.
  
  
  RESULTS
  Comparison of the matched pairs showed survival of the bilateral internal thoracic artery and single internal thoracic artery groups at 7, 10, 15, and 20 years was 89% versus 87%, 81% versus 78%, 67% versus 58%, and 50% versus 37%, respectively (p < 0.0001). Divergence of bilateral internal thoracic artery and single internal thoracic artery hazard function curves continued to widen through 20 postoperative years. At 20 years, bilateral internal thoracic artery grafting was predicted to produce worse survival in 2.8% of patients, a survival advantage of less than 5% in 12.9%, greater than 10% in 52%, and greater than 15% in 7.6%. Combinations of cardiac and noncardiac descriptors were used to define higher and lower risk patient subsets. Advanced age, abnormal left ventricular function and noncardiac risk factors decreased overall survival but the incremental benefit of bilateral internal thoracic artery grafting persisted.
  
  
  CONCLUSIONS
  Bilateral internal thoracic artery grafting produces improved survival compared with single internal thoracic artery grafting during the second postoperative decade, and the magnitude of that benefit increases through 20 postoperative years.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA. lytleb@ccf.org
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Lytle
authors.forename: Eugene H
authors.initials: EH
authors.lastname: Blackstone
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Sabik
authors.forename: Penny
authors.initials: P
authors.lastname: Houghtaling
authors.forename: Floyd D
authors.initials: FD
authors.lastname: Loop
authors.forename: Delos M
authors.initials: DM
authors.lastname: Cosgrove
mesh_terms: D003327:Coronary Disease / Q000145:classification / Q000401:mortality / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007387:Internal Mammary-Coronary Artery Anastomosis / Q000379:methods / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D016019:Survival Analysis; D016896:Treatment Outcome