Warm and tepid cardioplegia: do they provide equal myocardial protection?

Cardiac troponin I (CTnI) has been shown to be a marker of myocardial injury. The aim of this prospective, randomized study was to compare intermittent antegrade warm cardioplegia with tepid blood cardioplegia in patients undergoing first elective coronary artery bypass graft, using CTnI release as the criterion for evaluating the adequacy of myocardial protection.

Seventy patients were randomly assigned to one of two cardioplegia groups. CTnI concentrations were measured in serial venous blood samples drawn immediately before cardiopulmonary bypass and after aortic unclamping at 6, 9, 12, and 24 hours. Analysis of covariance with repeated measures was performed to test the effect of the type of cardioplegia and time on CTnI concentration.

The total amount of CTnI released (8.23 +/- 20.5 microg in the warm group and 3.19 +/- 2.4 microg in the tepid group) was not statistically different (p = 0.23). The CTnI concentration did not differ for any sample in either of the two groups when adjusted on ejection fraction and the number of preoperative myocardial infarctions (p = 0.06). No patient in the tepid group versus 4 patients in the warm group showed CTnI evidence of perioperative myocardial infarction (p = 0.12).

Our study showed no preference for warm or tepid cardioplegia in terms of myocardial protection, either for clinical or biological data.