Hyperhomocysteinemia, antithrombin consumption, and early venous graft closure in surgical coronary revascularization.

Hyperhomocysteinemia is a pathological condition that increases cardiovascular risk due to prothrombotic behaviour in the patient. This case report concerns a 61-year-old man undergoing surgical coronary revascularization for early thrombosis of the venous graft. The postoperative antithrombin activity was extremely low (33%), despite normal preoperative values (79%) and a short cardiopulmonary bypass. At a subsequent screening, the patient was diagnosed with hyperhomocysteinemia (18.4 mmol/L) due to a heterozygous C677T mutation of the enzyme methylenetetrahydrofolate reductase associated with a folate deficiency. Hyperhomocysteinemia and cardiac operation are both factors that induce increased thrombin formation, which may induce antithrombin consumption and a consequent thrombotic event. Further studies are needed to define hyperhomocysteinemia as an independent risk factor for thrombotic events after cardiac surgery.