title: Off-pump versus on-pump coronary artery bypass: does number of grafts performed represent a selection bias in comparative studies? Results from a matched cohort comparison.
abstract: BACKGROUND
  Several retrospective studies comparing off-pump and on-pump coronary surgery and the largest randomized studies published to date showed a lower number of grafts performed in patients submitted to off-pump coronary artery bypass surgery (OPCAB). These findings bring about the question of the general applicability of the results. We eliminated the selection bias correlated with the number of grafts per patient by comparing the short-term outcomes of patients undergoing OPCAB and standard coronary artery bypass grafting (CABG) matched for number of grafts.
  
  
  METHODS
  Eighty-seven consecutive patients undergoing OPCAB (group A) were selected from the database of our Institution during a 2-year period. Matching was performed by iterative selection prioritizing, in the following sequence: number of grafts, EuroSCORE, and age. A total of 87 patients operated upon with the on-pump technique represented the control group (group B).
  
  
  RESULTS
  There were no significant differences in preoperative characteristics between the two groups. The number of grafts per patient was 2.2 +/- 0.5 in group A and 2.2 +/- 0.5 in group B. Early mortality did not differ between the two groups and it was 2.2% (2 patients) in group A and 3.4% (3 patients) in group B (p = NS). The incidence of myocardial infarction did not differ between the two groups. No patient in either group had stroke or coma. Five (5.7%) patients in group A and 7 (8.0%) patients in group B had atrial fibrillation (p = NS).
  
  
  CONCLUSIONS
  We were unable to demonstrate any significant differences in short-term mortality or morbidity outcome between OPCAB and standard CABG patients Our findings suggest that excellent results can be obtained with both surgical approaches.
authors.affiliation: Department of Cardiac Surgery, St. Andrea Hospital, "La Sapienza" University, Rome, Italy. aroscitano@katamail.com
authors.forename: Antonino
authors.initials: A
authors.lastname: Roscitano
authors.forename: Umberto
authors.initials: U
authors.lastname: Benedetto
authors.forename: Fabio
authors.initials: F
authors.lastname: Capuano
authors.forename: Caterina
authors.initials: C
authors.lastname: Simon
authors.forename: Euclide
authors.initials: E
authors.lastname: Tonelli
authors.forename: Giovanni
authors.initials: G
authors.lastname: Ruvolo
authors.forename: Riccardo
authors.initials: R
authors.lastname: Sinatra
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology / Q000209:etiology; D016022:Case-Control Studies; D015331:Cohort Studies; D001026:Coronary Artery Bypass / Q000009:adverse effects; D047549:Coronary Artery Bypass, Off-Pump / Q000009:adverse effects; D003324:Coronary Artery Disease / Q000453:epidemiology / Q000503:physiopathology / Q000601:surgery*; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009203:Myocardial Infarction / Q000453:epidemiology / Q000209:etiology; D015983:Selection Bias; D016019:Survival Analysis; D016896:Treatment Outcome