In the U.S. alone, more than 30,000 women younger than 55 are hospitalized with acute myocardial infarction (AMI) each year. While an increased prevalence of this statistic has led to several national awareness campaigns and evidence-based guidelines, contemporary data trending clinical characteristics, hospitalizations and mortality rates of this population have been relatively non-existent. Amending this absence of information is a new study published July 21 in the Journal of the American College of Cardiology, which found that "AMI hospitalization rates for young people have not declined over the past decade." Further, "young women with AMIs have more comorbidity, longer length of stay, and higher in-hospital mortality than young men, although their mortality rates are decreasing."

Led by Aakriti Gupta, MBBS, Department of Internal Medicine, Yale School of Medicine, the investigation utilized the National Inpatient Sample, comparing clinical characteristics, AMI hospitalization rates, length of stay, and in-hospital mortality for patients with AMI across ages 30-54 years, dividing them into five-year subgroups from 2001-2010.

Calculating the data, Gupta and co-authors identified 230,684 hospitalizations with a principal discharge diagnosis of AMI in 30-54-year-old patients, resulting in an estimated 1,129,949 hospitalizations in the U.S. from 2001-2010. Of the young patients hospitalized with AMI, women represented approximately a quarter of the population (25.9 percent women; 74.1 percent men). Secondary analyses that involved race revealed that more women were black (19.7 percent) than men (10.5 percent).

Results showed that no significant declines were observed in AMI hospitalizations rates for patients younger than 55-years-old or stratified by sex. A prevalence of comorbidities however, was higher in women and increased among both sexes through the allotted study period. In secondary analyses, black women showed to have the highest prevalence of selected comorbidities including hypertension, heart failure, and diabetes, as compared with white women, black men and white men.

The study also showed that hospitalization rates for AMI were higher in men compared with women across all age subgroups. In addition, absolute number of discharges for AMI among women increased from 28,681 (56 per 100,000) in 2001 to 31,777 (61 per 100,000) in 2010, while absolute number of discharges for AMI among men decreased from 87,084 (174 per 100,000) to 86,734 (171 per 100,000). Though absolute declines were noted for the majority of male subgroups, women showed either no change or a slight absolute increase in hospitalization rates. In secondary analyses that included age-sex-race comparisons, black women had a much higher hospitalization rate than white women consistently from 2001 to 2010, while hospitalization rates were comparable between white and black men.

While women were prone to have longer length of stays and higher in-hospital mortality than men across all age groups, the study showed that their in-hospital mortality declined significantly between 2001-2010 (3.3 percent to 2.3 percent, relative change 30.5 percent, p-for-trend < 0.0001), but not for men (2.0 percent to 1.8 percent, relative change 8.6 percent, p-for-trend=0.6).

The authors conclude that moving forward, "mechanisms underlying the higher risks associated with AMI in young women than in men warrant further investigation to identify the sex-specific biological, clinical and social factors responsible." Further, "the racial differences in hospitalizations for AMI in young patients that were more pronounced among women compared with men warrant further investigation of potential causes."

In a corresponding editorial comment, Leslee J. Shaw, PhD, FACC, and Javed Butler, MD, MPH, FACC, add that "If we consider the current climate for health care reform and value based care, should we not consider health equity as a primary target for improving the lives of our diverse American culture that would maximally affect care for persistently identified high-risk subsets, including black women? Clearly, those efforts regulating sex and racial equity of care are those that ensure quality care for all."