Influence of folic acid on plasma homocysteine levels & arterial endothelial function in patients with unstable angina.

BACKGROUND & OBJECTIVE: High plasma homocysteine (Hcy) levels are known to be associated with coronary artery disease, but the precise level associated with an increased risk is yet controversial. Whether the beneficial effects of folic acid on arterial endothelial function persist over longer periods is not known. This study was carried out to assess whether folic acid supplementation could produce improvements in Hcy levels and arterial endothelial function in the patients with unstable angina (UA) and hyperhomocysteinaemia. METHODS: The plasma Hcy levels of 52 cases with UA and 30 control subjects were measured by using high-performance liquid chromatography (HPLC) with fluorescence detection, plasma folic acid and vitamin B(12) levels were also measured. The patients with hyperhomocysteinaemia were treated with 5 mg of folic acid for 8 wk, and then rechecked the plasma levels of Hcy, folic acid and vitamin B(12) at the end of 4(th) and 8(th) wk. Arterial endothelial function was measured as flow-mediated dilation of the brachial artery using high-resolution B-mode ultrasound in 22 cases with UA and hyperhomocysteinaemia before and after folic acid treatment. RESULTS: The plasma Hcy level was significant higher in the patients with UA than in the controls (19.2 +/- 4.9 vs 10.7 +/- 5.3 micromol/l, P<0.01). The plasma levels of folic acid and vitamin B12 were significant lower in the patients with UA than in the controls. There were 22(42.3%) patients with hyperhomocysteinaemia in UA group. After 4 and 8 wk of administration of folic acid, the Hcy level reduced by 20.3 and 55.3 per cent in the UA patients with hyperhomocysteinaemia, respectively. Flow-mediated dilation also improved significantly, from 6.4 +/- 1.9 to 9.0 +/- 1.2 per cent (P<0.05) after 8 wk treatment with folic acid. INTERPRETATION & CONCLUSION: Plasma Hcy level was elevated in patients with UA. Folic acid can reduce the plasma Hcy levels and improve arterial endothelial function in the UA patients with hyperhomocysteinaemia.