Assessment of myocardial injury by troponin T in off-pump coronary artery grafting and conventional coronary artery graft surgery

Purpose: The present study was undertaken to assess the degree of myocardial injury, using troponin T (TnT), in off-pump coronary artery surgery (OPCAB) and in a comparable patient group undergoing conventional coronary artery graft surgery (CABG). Methods: Twenty-seven OPCAB and 27 CABG patients were investigated. Blood samples for TnT were taken at intubation and at 12, 24 and 72 h. Nine patients (five OPCAB, four CABG) underwent 2 h sampling for 12 h for the assessment of the TnT release profile. All patients had an electrocardiogram performed preoperatively and on the mornings of days 1 and 5 postoperatively. Results: The OPCAB group had significantly greater Canadian Heart Classification 3 patients (P = 0.003): however, other demographic data were similar between the two groups. All patients had normal TnT at initial sampling. The mean number of grafts in each group was 1.8 +/- 0.6 for OPCAB and 1.9 +/- 0.3 for CABG (P = NS). There were two new Q wave myocardial infarctions in the CABG group and none in the OPCAB group. These cases were excluded from biochemical analyses. Troponin T release was significantly less in the OPCAB group at 12 and 24 h (P < 0.001 and P = 0.03, respectively). Peak TnT release Occurred at 6-8 h in both groups. Troponin T release was significantly lower in the OPCAB group at 2, 4, 6, 8, 10 and 12 h (P = 0.01, P = 0.03, P = 0.02, P = 0.02, P = 0.03 and P = 0.04, respectively). Postoperatively, the OPCAB group required less blood transfusion (P = 0.02). Conclusions: The OPCAB group demonstrated a significantly reduced TnT release profile compared with the CABG group.