Acute Myocardial Infarction in Pregnancy

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.