[Myocardial infarction and oral contraceptives]

Shortly after the introduction of oral contraceptives in 1960, myocardial infarction (MI) started to emerge as a major adverse effect. Its mechanism and pathophysiology have remained elusive. Many epidemiological studies identified smoking, hypertension, diabetes and hypercholesterolemia as risk factors for coronary thrombosis in young women using oral contraceptives. The pathogenesis of MI involves two phases: atherosclerotic plaque formation, and thrombotic arterial occlusion. The use of very low doses of estrogen (less than 50 microg of ethinyl estradiol) and new progestagens have minimized the vascular risks. However, the risk remains in women who smoke or have other atherosclerotic risks factors. We report 12 cases of MI in women aged 35 +/- 5 years who were using different types of oral contraceptive. All the women had several risks factors, such as smoking, hypertension, hypercholesterolemia, obesity, and type II diabetes. Coronarography during the acute phase showed either occlusions on severe atherosclerotic stenoses or thrombosis of arteries with non significant atherosclerotic plaque. In two cases coronarography was normal after thrombolysis. Ten women recovered without sequelae, but reversible left ventricular dysfunction occurred in the other two women, who did not have acute-phase revascularization. Recent case-control studies show that the cardiovascular risk is very low with new, third-generation combined contraceptives. But the risk of MI increases with age, smoking, hypertension, dyslipidemia and diabetes. The absolute risks associated with oral contraceptives and smoking are higher in women over 35, because of the steeply rising incidence of atherosclerosis. It is mandatory to respect the classical contraindications of oral contraception.