BACKGROUND Transmyocardial laser revascularization (TMLR) is a modem approach in the management of coronary artery disease. It can be considered as a method of choice in some cases unsuitable for coronary angioplasty or bypass grafting. Transmyocardial laser revascularization is expected to relieve angina and to improve patient quality of life and survival. The aim of the study was to determine whether the laser energy released during TMLR induces any myocardial deterioration, which could affect the heart status and function in early postoperative period. METHODS A group of 80 patients with CAD (37 TMLR/CABG, 43 CABG) was evaluated within 24 hours after the procedure for CK-MB and cTnT concentrations to determine myocardial injury. Elective hemodynamic indexes were used to determine the heart function. The cardiac rhythm disturbances were recorded by Holter monitoring. Homeostatic disturbances and postoperative complications were also recorded. RESULTS The postoperative CK-MB and cTnT levels were significantly higher in the TMLR g roup (ANOVA: p < 0.001 and p = 0.013), with significantly high correlation of laser energy and number of channels with CK-MB(max) concentration (Pearson coefficient of correlation 0.614 and 0.561, p < 0.0001) and non significant correlation with cTnT(max) concentration. No significant differences between the TMLR and the CABG group regardinghemodynamic indexes were observed. Significantly more patients in the TMLR group had ventricular events (VE) within 24 postoperative hours (27 vs 10, chi 2: p < 0.0001), reguiring antyarrhythmic drugs administration (13 vs 2, chi2: p < 0.0008). The number of channels created in a group of patients with VE was significantly higher (21.8+/- 7.66 vs 15.7 +/- 7.63; p = 0.0255). No significant difference in postoperative blood loss was observed. Significantly more patients from the TMLR group received blood (37/37 vs 36/43 in CABG group, chi2: p = 0.029), but no significant difference in number of blood units used was observed (3.22 +/- 1.8 U. in TMLR group vs 2.92 +/- 1.52 U. in CABG group: p = 0.445). Significantly more patients needed postoperatively inotropic support in the TMLR group (10 vs 2, chi2; p = 0.019). One patient from the TMLR group had low output syndrome (IAB support) and one from the CABG group had postoperative myocardial infarction. CONCLUSION The laser energy released during TMLR injures th e myocardium (CK-MB, cTnT, VE) but does notaffect the heart function (hemodynamic status, postoperative course).