Elevated Lp(a) is the most frequent familial lipoprotein disorder leading to premature myocardial infarction in a country with low cholesterol levels

Disorders of the lipoprotein metabolism are an important cause of premature coronary artery disease and myocardial infarction. Of the genetic lipoprotein disorders, elevation of apoprotein (apo) B containing lipoproteins is the most frequent one in the western population. We aimed to define the prevalence of genetic lipoprotein disorders and other risk factors in a population from a country with a low average cholesterol levels. We examined 48 consecutive patients with premature myocardial infarction below age 55, their 78 siblings and age and body mass index matched controls for familial lipoprotein disorders. The patients with premature myocardial infarction had higher triglyceride, low-density lipoprotein, apo B, lipoprotein (Lp) (a) and lower apo A1 levels then controls (p<0.05). Of the nonlipid risk factors, 67% smoked, 8% had diabetes mellitus, 17% had hypertension and 58% a family history of premature coronary artery disease. Fifty percent of these patients with premature myocardial infarction had a familial lipoprotein disorder. Familial excess of Lp(a) was the most frequent lipoprotein abnormality present in 16% of the patients followed by familial combined hyperlipidemia. We conclude that, Lp(a) increase was the most frequent familial lipoprotein abnormality in this population. The frequency of familial lipoprotein disorders in this population emphasises the need to screen siblings of patients with premature myocardial infarction.