PLASMA TOTAL HOMOCYSTEINE, VITAMIN-B, AND RISK OF CORONARY ATHEROSCLEROSIS

Epidemiological research has shown that elevated plasma total homocyst eine (tHcy) is a risk factor for atherosclerotic disease. In the prese nt case-control study, we investigated whether fasting or postmethioni ne-loading tHcy was a stronger predictor of risk of severe coronary at herosclerosis. Furthermore, we studied levels of B vitamins, which are involved in homocysteine metabolism. Subjects were recruited from men and women, aged 25 to 65 years, who underwent coronary angiography be tween June 1992 and June 1994 in a hospital in Rotterdam, The Netherla nds. Cases (n=131) were defined as those with greater than or equal to 90% occlusion in one and greater than or equal to 40% occlusion in a second coronary artery, while control subjects (n=88) had less than or equal to 50% occlusion in only one coronary vessel. In addition, a po pulation-based control group free from clinical cardiovascular disease (n=101) was studied. Coronary patients were studied at least 2.5 mont hs after angiography or other acute illness, such as myocardial infarc tion. After adjusting for age and sex differences between the groups, cases had 9% (P=.01) higher geometric mean fasting and 7% (P=.04) high er geometric mean postload tHcy than the combined control groups. Desp ite higher levels of tHcy for cases, their geometric mean levels of re d cell folate and pyridoxal 5'-phosphate were higher than for control subjects, whereas plasma vitamin B-12 was only slightly lower in cases . The frequency distribution of tHcy values in cases was slightly shif ted toward the right, across the entire range, compared with the distr ibution in the combined control group. This was somewhat more obvious for fasting than postload tHcy levels. The odds ratio (OR) for severe coronary atherosclerosis (case status) for each 1 SD increase in fasti ng tHcy (5 mu mol/L) was 1.3 (95% confidence interval [CI], 1.0-1.6), similar to the OR for each 1 SD increase (12 mu mol/L) in postmethioni ne-loading tHcy (1.3 [95 CI, 1.0-1.7]), after adjustment for sex, age, and other potential confounders. Furthermore, there was a significant linear trend of increasing fasting tHcy with increasing number of occ luded arteries (P=.01), correcting for sex, age, and other potential c onfounders. Our data show a positive association between plasma tHcy a nd risk of severe coronary atherosclerosis, of similar strength for fa sting and postload tHcy levels. The data suggest that the association exists over a wide range of tHcy levels, without a clear cutoff point below which there is no increased risk.