Cardiac Troponin T Levels in On- and Off-Pump Coronary Artery Bypass Surgery

BACKGROUND: Conventional coronary artery bypass graft surgery (CCAB) has been associated with greater myocardial injury than off-pump surgery (OPCAB). However, the extent of myocardial injury following CCAB and OPCAB has not been assessed by priority of surgery or the number of diseased vessels. We tested the hypothesis that the additional myocardial injury associated with CCAB compared with OPCAB is sustained when patients are stratified by priority and 2- or 3-vessel disease. METHODS AND RESULTS: In this prospective cohort, we measured 24-hour postoperative cardiac troponin T (cTnT) following CCAB and OPCAB surgery to determine if OPCAB results in less perioperative myocardial damage by priority (urgent or elective). We studied 1511 patients who underwent heart surgery in one hospital in northern New England between 2000 and 2004. Surgeons used either CCAB (778 patients) of OPCAB (733 patients). Unpaired t tests were used to test the mean difference in cTnT between CCAB and OPCAB subgroups. Mean cTnT levels were significantly higher in the CCAB group (0.94 ng/mL) than the OPCAB group (0.18 ng/mL) with P < .001; this difference was consistent across urgent and elective surgeries, and patients with both 2- and 3-vessel disease. CCAB patients consistently demonstrated higher cTnT levels. Similar results were evident when stratified by patient characteristics and surgeon. CONCLUSIONS: In summary, higher postoperative cTnT levels are associated with CCAB than with OPCAB, regardless of priority, number of diseased vessels, patient characteristics, or surgeon. OPCAB results in less myocardial injury in patients, whether they present with 2- or 3-vessel disease and whether they undergo urgent or elective cardiac surgery.