Pre-operative homocysteine levels and morbidity and mortality following cardiac surgery

AIMS: Elevated homocysteinaemia is associated not only with an increased risk for cardiovascular disease but also for increased morbidity and mortality in patients with established coronary artery or cerebrovascular disease. Whether elevated homocysteine further increases the morbidity and mortality in patients undergoing cardiac surgery on cardiopulmonary bypass (CPB) (a prothrombotic state itself) remains less known. METHODS AND RESULTS: Accordingly, we conducted a prospective observational study with pre-operative measurement of plasma homocysteine levels in 531 consecutive patients undergoing cardiac operations on CPB. The association of pre-operative plasma homocysteine levels with post-operative morbidity and hospital mortality was evaluated. Elevated homocysteine levels (>15 µmol/L) were observed in 209 patients (39.4%), and homocysteinaemia was associated with a higher mortality and perioperative morbidity (major morbidity, low cardiac output, acute renal failure, mesenteric infarction, and thrombo-embolic events). Even after accounting for the differences in baseline clinical features, EuroSCORE, and CPB time, pre-operative homocysteine levels remained independently associated with hospital mortality [odds ratio (OR) 1.06, 95% confidence interval (CI) 1.03–1.11], major morbidity (OR 1.04, 95% CI 1.01–1.07), low cardiac output (OR 1.04, 95% CI 1.02–1.08), mesenteric infarction (OR 1.06, 95% CI 1.01–1.11), and thrombo-embolic events (OR 1.09, 95% CI 1.04–1.13). This association of homocysteine with increased risk of morbidity and mortality was observed particularly in CABG patients. CONCLUSION: Elevated pre-operative homocysteine level is independently associated with increased morbidity and mortality, particularly in patients undergoing CABG. Specific post-operative antithrombotic strategies may be advisable in hyperhomocysteinaemic patients.