Plasma homocyst(e)ine levels and graded risk for myocardial infarction: findings in two populations at contrasting risk for coronary heart disease.

Standardized mortality rates for coronary heart disease (CHD) in men are about 3-fold higher in Northern Ireland than in France. The differences could not be explained by the presence of conventional risk factors for atherosclerosis. We studied in subjects from these two countries, an additional risk factor, namely, concentration of plasma homocyst(e)ine which is frequently elevated in patients with CHD. We measured the plasma concentration of homocyst(e)ine in survivors of myocardial infarction (MI) and in control subjects from the Belfast, Strasbourg and Lille regions. Plasma homocyst(e)ine levels were higher in the Irish than in the French controls; subjects with MI had higher levels than controls. Results were compatible with global excess of risk for MI being graded across the distribution of plasma homocyst(e)ine concentrations, although the trends lost significance in Belfast after adjustment for other risk factors. The higher plasma homocyst(e)ine concentrations we observed in the Irish population could be the reason for the different CHD mortality rates. This epidemiological observation could prompt dietary and vitamin supplementation studies aimed at decreasing homocyst(e)ine levels as well as the incidence of arterial occlusive disease, under controlled conditions in high risk populations.