Changing Incidence and Mechanism of Pregnancy-Associated Myocardial Infarction in the State of California

Background The objective of this study was to evaluate the temporal trends in pregnancy-associated myocardial infarction (PAMI) in the State of California and explore potential risk factors and mechanisms. Methods and Results The California State Inpatient Database was analyzed from 2003 to 2011 for patients with International Classification of Diseases, Ninth Revision (ICD-9) codes for acute myocardial infarction and pregnancy or postpartum admissions; risk factors were analyzed and compared with pregnant patients without myocardial infarction. A total of 341 patients were identified with PAMI from a total of 5 266 380 pregnancies (incidence of 6.5 per 100 000 pregnancies). Inpatient maternal mortality rate was 7%, and infant mortality rate was 3.5% among patients with PAMI. There was a nonsignificant trend toward an increase in PAMI incidence from 2003 to 2011, possibly attributable to higher incidence of spontaneous coronary artery dissection, vasospasm, and Takotsubo syndrome. PAMI, when compared with pregnant patients without myocardial infarction, was significant for older age (aged >30 years in 72% versus 37%, P<0.0005), higher preponderance of Black race (12% versus 6%, P<0.00005), lower socioeconomic status (median household income in lowest quartile 26% versus 20%, P=0.04), higher prevalence of hypertension (26% versus 7%, P<0.0005), diabetes (7% versus 1%, P<0.0005), anemia (31% versus 7%, P<0.0001), amphetamine use (1% versus 0%, P<0.00005), cocaine use (2% versus 0.2%, P<0.0001), and smoking (6% versus 1%, P=0.0001). Conclusions There has been a trend toward an increase in PAMI incidence in California over the past decade, with an increasing trend in spontaneous coronary artery dissection, vasospasm, and Takotsubo syndrome as mechanisms. These findings warrant further investigation.