RESUMO
BACKGROUND: The aim of the present study was to ascertain the percentage of left apical myocardial apoptosis in three-vessel coronary artery bypass grafting patients quantitatively and the impact of ischemic preconditioning. METHODS: Twenty-one patients with three-vessel disease who had elective coronary artery bypass grafting were randomized in a ratio of 2:1 to ischemic preconditioning (n = 14) or a control group (n = 7). The ischemic preconditioning protocol was established by two cycles of ascending aorta occlusion for 2 minutes followed by 3 minutes of reperfusion. Myocardial samples from the apex of the left ventricle were taken using a Tru-Cut needle before aortic cross-clamping and immediately after declamping. The percentage of apoptosis was analyzed by TUNEL methods. Data on hemodynamics and biochemical markers were collected. RESULTS: Low levels of myocardial apoptosis were found before the operation (0.01% +/- 0.00%). During the early reperfusion period, the percentage of myocardial apoptotic cells significantly increased (0.15% +/- 0.05%, p = 0.008). Ischemic preconditioning significantly improved cardiac index and right ventricular ejection fraction recovery after the operation (p = 0.036 and 0.001 respectively, repeated measure) but had no effect on myocardial apoptosis before and after the operation (0.01 +/- 0.00 versus 0.01 +/- 0.00, p = 0.658 and 0.12% +/- 0.04% versus 0.23% +/- 0.14%, p = 0.302). CONCLUSIONS: Cardioplegic myocardial ischemia during open heart operation was associated with induction of cardiomyocyte apoptosis in humans. Attenuation of postoperative cardiac dysfunction by ischemic preconditioning appeared to be independent of apoptosis.
