RISK OF PRIMARY AND RECURRENT ACUTE MYOCARDIAL-INFARCTION FROM LIPOPROTEIN(A) IN MEN AND WOMEN

Objectives. This study sought to examine whether lipoprotein(a) concen trations were risk factors for a first acute and recurrent myocardial infarction. Background. There is conflicting evidence concerning the r isk of acute myocardial infarction from lipoprotein(a). No studies hav e examined the risk of recurrent acute myocardial infarction from lipo protein(a), and few have addressed the risk in women. Methods. This wa s a population-based case-control study of 893 men and women 35 to 69 years old participating in the World Health Organization Monitoring Tr ends and Determinants in Cardiovascular Disease (MONICA) Project in Ne wcastle, Australia in 1993 to 1994. Case and control patients were cla ssified into those with and without a previous myocardial infarction, and median lipoprotein(a) concentrations were compared after adjusting for other variables. Quintiles of lipoprotein(a) concentration were a lso examined. Results. Compared with control subjects without a previo us myocardial infarction, median lipoprotein(a) concentrations increas ed from case patients with a first myocardial infarction (15 mg/liter higher, 95% confidence interval [CI] -36 to 60) to control patients wi th a previous myocardial infarction (159 mg/liter higher, 95% CI 40 to 278) and case patients with a previous myocardial infarction (60 mg/l iter higher, 95% CI -16 to 1.36, p < 0.01, test for trend). Women had significantly higher lipoprotein(a) concentrations than men (median 71 mg/liter higher, 95% CI 23 to 118). The highest quintile of lipoprote in(a) (>550 mg/liter) was a significant risk factor for a first acute myocardial infarction (odds ratio [OR] 1.77, 95% CI 1.03 to 3.03); but in those with a previous myocardial infarction, the highest quintile was not associated,vith recurrent myocardial infarction (OR 0.84, 95% CI 0.30 to 2.37). Conclusions. High lipoprotein(a) concentrations may be a marker of vascular or tissue injury or may be associated with oth er genetic or environmental factors that cause acute myocardial infarc tion. Currently, lipoprotein(a) measurement cannot be recommended for assessment of risk for acute myocardial infarction.