Oral contraceptives and myocardial infarction.

During 1965-9 22 women aged 41 years or less have been seen with myocardial infarction. Eleven had been taking oral contraceptives. This prevalence of oral contraception (50%) is appreciably greater than that estimated for women of the same age in the general population.Nine of these 11 women had an independent increased risk of developing ischaemic heart disease because of hyperlipidaemia, hypertension, or excessive cigarette smoking. Ten of the 11 not taking an oral contraceptive also had a readily identifiable predisposing factor. None of the 22 showed carbohydrate intolerance. The similarity of the two groups is the striking finding. Details of 15 women of comparable age seen during 1960-4 before oral contraceptives were widely used are also presented, and they had similar characteristics.Oral contraceptives do not appear on their own to increase the risk of developing myocardial infarction, but they may do so in women otherwise prone to ischaemic heart disease. Suggestions are made for the identification of these women.