BACKGROUND: We determined that cold blood cardioplegia and intermittent ventricular fibrillation with ischemia were associated with similar enzyme and myocardial protein leakage in a randomized, prospective study of 40 patients. We have continued to use both methods in our unit, according to surgeons' preference. METHODS: In our database we have reviewed 1,923 patients who have undergone first-time elective or urgent coronary artery bypass grafting from January 1992 to May 1997. RESULTS: Five hundred seventy-eight patients underwent coronary artery bypass grafting with cold blood cardioplegia and 1,345 had ventricular fibrillation and aortic cross-clamping. The preoperative factors were virtually identical. Intraoperative differences were only those inherent to the two techniques: temperature and cross-clamp time. Mortality was 2.5% for ventricular fibrillation and aortic cross-clamping arrest and 2.1% for cardioplegia (p=0.55 by chi2 test). There was a higher use of the intraaortic balloon pump in the ventricular fibrillation and aortic cross-clamping group (2.4% versus 1.0%; p=0.04), but no other differences in outcome were detected. CONCLUSIONS: A truly randomized trial to demonstrate which technique is superior is impractical at this level of difference because it would require 37,000 patients to avoid a beta error. We have to base our practice on the retrospective data available. Each technique has its merits in practice, which are discussed.