A prospective randomized study of diluted versus non-diluted cardioplegia (minicardioplegia) in primary coronary artery bypass surgery

Aim. Sanguineous (blood) cardioplegia has been established as the prime option for myocardial protection but the choice of dilution (4:1 blood to crystalloid ratio) versus use of blood from the cardiopulmonary bypass alone (minicardioplegia) remains controversial. The purpose of this prospective randomized clinical trial was to compare the clinical outcome and enzymatic endpoints (troponin I, CK-MB isoenzyme release) in patients undergoing primary CABG surgery. Methods. From June 1999 to October 2000, 59 patients were randomized preoperatively to undergo coronary artery bypass grafting surgery using cardiopulmonary bypass and either diluted (4:1 blood to crystalloid ratio; n = 25) or undiluted sanguineous cardioplegia (minicardioplegia; n = 4) at the Montreal Heart Institute. Clinical data and biochemical markers of ischemia were recorded. Tepid cardioplegia and moderate hypothermic cardiopulmonary bypass were used in 92% of patients. Results. There were no significant differences in preoperative variables between the 2 groups. There were no statistically significant differences in low output syndrome, stroke rate, arrhythmia or hospital length of stay between both groups. There was no statistically significant difference between minicardioplegia and diluted groups in the release of troponin T 24 hours postoperatively (0.36 +/- 0.31 versus 0.23 +/- 0.22, respectively). There was a slightly higher release of troponin T in the minicardioplegia group 48 hours after surgery (0.38 +/- 0.35 versus 0.20 +/- 0.16) (p = 0.03) and of CK-MB 24 hours postoperatively (22.9 +/- 18.6 versus 10.2 +/- 5.3) (p < 0.01). Conclusion. Clinical outcomes are similar in patients undergoing primary CABG surgery with tepid cardioplegia, and moderate hypothermic bypass with diluted or minicardioplegia. Minicardioplegia may be the optimal method of myocardial protection because of low cost, ease of use and lack of hemodilutive effect.