Homocysteine Affects Outcome of Cardiac Transplants

In an animal study, high levels of homocysteine were found to increase the risk of chronic rejection in heart transplant patients. The study suggests that heart transplant patients may be able to reduce this risk by changing their diet to include vitamins B12, B6, or folate in advance of surgery to keep homocysteine levels low. The findings were reported at the annual Clinical Congress of the American College of Surgeons in Chicago (IL, USA).

In the study, one group of animals were fed a diet high in methionine and low in folate, while control animals received a normal diet. After two weeks, the experimental animals developed hyperhomocysteinemia with levels about 20 times higher than controls. In these animals, cardiac transplant grafts survived only 59 days, while grafts in animals receiving a normal diet survived an average of 107 days. The time to onset of rejection was also accelerated in the animals on a high homocysteine diet, averaging 42 days in test animals and 66 days in controls.

The researchers focused on studying homocysteine because of its known relationship to the development of atherosclerosis. In the study, high homocysteine levels are assumed to have contributed to the atherosclerotic process, which decreased the blood supply to cardiac grafts and caused the grafts to fail. The research was conducted by Dr. Susan L. Orloff, of the Oregon Health Sciences University (Portland, USA), and colleagues.

"This animal study shows that we can cause high levels of homocysteine and demonstrate a cause-and-effect relationship with vascular disease in cardiac grafts,” explained Dr. Orloff.