INCREASE IN TOTAL PLASMA HOMOCYSTEINE CONCENTRATION AFTER CARDIAC TRANSPLANTATION

Objective: To determine whether plasma homocysteine concentrations are increased in patients after cardiac transplantation. Design: Total pl asma homocysteine concentration was measured in 44 consecutive patient s before and at 3, 6, and 12 months after orthotopic heart transplanta tion between June 1, 1988, and Oct. 15, 1992, and the data were analyz ed statistically. Results: Mean homocysteine concentrations (normal ra nge, 4 to 17 mu mol/L) increased 70% from 12.5 mu mol/L before cardiac transplantation to 21.2 mu mol/L (P<0.002) 3 months after transplanta tion, at which time the concentrations were above normal in 14 of 26 p atients (54%). Homocysteine concentrations remained elevated 6 and 12 months after transplantation (20.4 and 22.6 mu mol/L, respectively) bu t did not increase further. Mean concentrations of plasma folic acid a nd vitamin B-12, cofactors in homocysteine metabolism, decreased 20% a nd 49%, respectively, within 3 months after transplantation (11.6 to 9 .3 mu g/L [P = 0.04] and 584 to 295 ng/L [P = 0.01]). The mean glomeru lar filtration rate decreased 25% during this same interval (81 to 61 mL/min; P = 0.0001). Linear regression analysis revealed an associatio n between the increase in homocysteine concentration and the folic aci d concentration that approached statistical significance (P = 0.07); w e found no statistically significant correlates of the increase in hom ocysteine concentration. Conclusion: The homocysteine concentration in creases in most patients within 3 months after cardiac transplantation to levels previously associated with premature atherosclerotic corona ry artery disease, and it remains increased for at least 1 year. Furth er investigation into the mechanism for the increase in homocysteine c oncentration and the relationship between homocysteine and coronary ar tery disease after transplantation is warranted.