Acute myocardial infarction in pregnancy - A United States population-based study

Background - The purpose of this study was to determine the incidence, mortality, and risk factors for pregnancy-related acute myocardial infarction in the United States. Methods and Results - The Nationwide Inpatient Sample for the years 2000 to 2002 was queried for all pregnancy-related discharges. A total of 859 discharges included a diagnosis of acute myocardial infarction, for a rate of 6.2 (95% confidence interval [CI] 3.0 to 9.4) per 100 000 deliveries. Among these, there were 44 deaths, for a case fatality rate of 5.1%. The odds of acute myocardial infarction were 30-fold higher for women aged 40 years and older than for women < 20 years of age. Single independent variables that were statistically and clinically significant, including age, race, and certain medical conditions and obstetric complications, were entered into a multivariable logistic regression model. Hypertension ( odds ratio [ OR] 21.7, 95% CI 6.8 to 69.1), thrombophilia ( OR 25.6, 95% CI 9.2 to 71.2), diabetes mellitus ( OR 3.6, 95% CI 1.5 to 8.3), smoking ( OR 8.4, 95% CI 5.4 to 12.9), transfusion ( OR 5.1, 95% CI 2.0 to 12.7), postpartum infection ( OR 3.2, 95% CI 1.2 to 10.1), and age 30 years and older remained as significant risk factors for pregnancy- related acute myocardial infarction. Black race was eliminated as a risk factor in the multivariable analysis, which suggests that the increased incidence among black women is explained by an increased prevalence of other cardiovascular risk factors. Conclusions - Although acute myocardial infarction is a rare event in women of reproductive age, pregnancy increases the risk 3- to 4-fold. Certain medical conditions and complications of pregnancy increase the risk further and are potentially modifiable risk factors.