Myocardial injury during off-pump surgery : The effect of intraoperative risk factors

To achieve better outcomes, the degree of myocardial injury due to off-pump coronary artery bypass surgery (OPCAB) must be reduced. We studied the factors that render patients scheduled for OPCAB vulnerable to myocardial injury, using troponin T (cTnT) as a marker of myocardial injury. We prospectively investigated 123 patients being operated by a group of surgeons with off-pump technique between January 2001 and June 2006 in Siyami Ersek Thoracic and Cardiovascular Surgery Center. Myocardial injury occurring during surgery was assessed by post-operative cTnT measurement. Then, the relation between intraoperative factors and postoperative cTnT release were statistically evaluated. Blood samples for cTnT measurement were taken from all patients before operation, immediately after arrival at the intensive care unit, then at 6, 12, and 24 hours after distal revascularization. When regarding the intraoperative risk factors, we found that the heart rate, blood pressure and anastomosis time are the main determinant of myocardial cell injury occurring during OPCAB surgery. Although aortic cross-clamp and cardioplegic arrest were not used in off-pump myocardial revascularization, the ischemic myocardial cell destruction was also inevitable in off-pump technique. Therefore, management of heart rate and myocardial contractility was desirable not only for precise anastomosis but also for myocardial protection during OPCAB surgery.