Early and midterm outcome after off-pump and on-pump surgery in Beating Heart Against Cardioplegic Arrest Studies (BHACAS 1 and 2): a pooled analysis of two randomised controlled trials
BACKGROUND
Although no randomised controlled trial has assessed the midterm effects of coronary-artery bypass surgery on the beating heart, this technique is being used in more and more patients. We did two randomised trials to compare the short-term morbidity associated with off-pump and on-pump myocardial revascularisation. Our aim was to pool the results to assess midterm outcomes.


METHODS
From March, 1997, to November, 1999, we randomly allocated 200 patients to off-pump and 201 to on-pump coronary surgery. In Beating Heart Against Cardioplegic Arrest Study (BHACAS) 1, we excluded patients who had had myocardial infarction in the past month or who required grafting of the circumflex artery distal to the first obtuse marginal branch. In BHACAS 2, we included such patients. Primary outcomes were all-cause mortality and cardiac-related events at midterm follow-up (1-3 years). Analysis was by intention to treat.


FINDINGS
Analyses of combined data from both trials showed the following risk differences with off-pump compared with on-pump surgery: atrial fibrillation -25% (95% CI -33% to -16%); chest infection -12% (-19% to -5%); inotropic requirement -18% (-25% to -10%); transfusion of red blood cells -31% (-41 to -21); and hospital stay longer than 7 days -13% (-21 to -5). Mean follow-up was 25 0 months (SD 9.1) for BHACAS 1 and 13.7 months (5 5) for BHACAS 2. Four (2%) of 200 patients in the off-pump groups died from any cause, compared with seven (3%) of 201 in the on-pump group (hazard ratio 0.57, 95% CI 0.17-1.96). 33 (17%) of 200 patients in the off-pump group died or had a cardiac-related event, compared with 42 (21%) of 201 in the on-pump group (0.78, 0 49-1.22).


INTERPRETATION
Off-pump coronary surgery significantly lowers in-hospital morbidity without compromising outcome in the first 1-3 years after surgery compared with conventional on-pump coronary surgery.