HYPERHOMOCYSTEINAEMIA AND PREMATURE CORONARY-ARTERY DISEASE IN THE CHINESE

Objectives-To examine the prevalence of hyperhomocysteinaemia and comp are it with the classic risk factors and vitamin status in Hong Kong C hinese patients with premature atherosclerotic coronary artery disease . Design-Case-control study. Setting-General hospital and community. S ubjects-Forty five patients (39 males) with significant coronary arter y disease confirmed by angiography (32 post myocardial infarction) and 23 healthy volunteers (17 male), all aged less than 55 years. Interve ntion-Standardised methionine-loading test. Main outcome measures-Coro nary artery disease, risk factors. Results-More patients than controls had fasting hyperhomocysteinaemia (10/45 v 2/23, P = 0.122), post-met hionine hyperhomocysteinaemia (17/45 v 1/23, P= 0.008), and an abnorma l response to methionine (15/45 v 1/23, P = 0.015). A history of smoki ng was more frequent in patients (3/23 v 25/45, P = 0.002). Sixteen of 17 patients with hyperhomocysteinaemia but only nine of 28 with normo homocysteinaemia were smokers (P = 0.0002). Fasting plasma cholesterol concentrations (mean (SD)) were higher in hyperhomocysteinaemia patie nts (6.41 (1.58) mmol/l) than in controls (5.53 (0.90) mmol/l) (P = 0. 042). Serum vitamin B-12 was not reduced and serum folate was higher i n hyperhomocysteinaemic patients (35 (4) nmol/l) than normohomocystein aemic patients (26 (9) mmol/l) (P = 0.009). Conclusions-Although the p revalence of hyperhomocysteinaemia in Hong Kong Chinese is similar to that in white subjects, hyperhomocysteinaemia is not an independent ri sk factor for coronary artery disease and is associated with smoking. This may be of some consequence in view of the change to a more Wester n diet with more animal protein, and therefore methionine, coupled wit h a high frequency of cigarette smokers in this region. The causes of the hyperhomocysteinaemia are multifactorial but in this pilot study a deficiency of folate and/or vitamin B-12 did not seem to be one of th em.