Hyperhomocysteinemia and transplant coronary artery disease

Background. Transplant coronary artery disease (TCAD) is a major cause of morbidity and mortality among heart transplant recipients. A variety of immunologic and nonimmunologic mechanisms are involved in the pathogenesis of the disease. Hyperhomocysteinemia has been recognized as an important risk factor for atherosclerotic vascular disease. The purpose of this article is to evaluate the prevalence of hyperhomocysteinemia in heart transplant recipients but more specifically to assess the published literature regarding the association between hyperhomocysteinemia and TCAD. Methods. A MEDLINE search using the key words hyperhomocysteinemia, transplant coronary artery disease, and heart transplant was performed. Results. Hyperhomocysteinemia has been commonly found among heart transplant recipients (average prevalence 51% to 76%). Worsening renal function and impaired vitamin metabolism seem to be the major causes of hyperhomocysteinemia in this particular population. TCAD has been found to be more prevalent and severe among patients with higher serum homocysteine levels. Vitamin supplementation is safe and effective in reducing serum homocysteine among heart transplant recipients. Conclusion. A large, long-term, double-blind, placebo-controlled prospective trial aimed at assessing the clinical significance of homocysteine-lowering therapy on the natural history of TCAD seems warranted.