A new Yale study has identified for the first time which risk factors are more likely to trigger a heart attack or acute myocardial infarction (AMI) in men and women under the age of 55.
Researchers discovered significant gender differences in risk factors associated with AMI and in the strength of associations in young adults, suggesting the need for a gender-specific prevention strategy. For example, high blood pressure, diabetes, depression and poverty had stronger associations with AMI in women compared to men, they found.
The study was published in JAMA Network Open on May 3rd.
While heart attacks are commonly associated with older adults, this population-based case-control study examined the relationship between a wide range of AMI-related risk factors in younger adults. The researchers used data from 2,264 AMI patients from the VIRGO study (Variation in Recovery: Role of Gender on Outcomes of Young Acute Myocardial Infarction Patients) and 2,264 population-based controls grouped by age, sex and race from the National Health and Nutrition Examination survey (NHANES).
The most important finding is that young men and women often have different risk factors. Seven risk factors — including diabetes, depression, hypertension or hypertension, current smoking, family history of AMI, low household income, and high cholesterol — have been associated with a higher risk of AMI in women. The highest association was diabetes, followed by current smoking, depression, hypertension, low household income, and family history of AMI. In men, current smoking and family history of AMI were the leading risk factors.
Rates of AMI in younger women have increased in recent years, said Yuan Lu, an assistant professor at the Yale School of Medicine and the study’s lead author.
“Young women with AMI are an unusual or extreme phenotype because of their age,” she said. “In the past, we have found that young women, but not older women, are twice as likely to die from AMI than men of the same age from AMI by gender.”
Population-attributable risk analysis was used to measure the impact of various risk factors at the population level. The study found that seven risk factors, many of which are potentially modifiable, together accounted for the majority of the overall risk of AMI in young women (83.9%) and young men (85.1%). Some of these factors — including high blood pressure, diabetes, depression and poverty — have a greater impact on young women than young men, Lu and her colleagues found.
“This study shows the importance of specifically targeting young women with heart attacks, a group that has been largely neglected in many studies and yet is about as large as the number of young women diagnosed with breast cancer,” said Dr . Harlan M. Krumholz, Harold H. Hines Jr. Professor of Medicine at Yale, Director of the Center for Outcomes Research and Evaluation (CORE) and senior paper author.
Raising awareness among doctors and young patients is a first step, the researchers said. National initiatives, such as the American Heart Association’s “Go Red for Women” campaign, should be expanded to raise awareness of the risk of cardiovascular disease in young women, they said. Healthcare providers must also identify effective strategies to improve the optimal delivery of evidence-based AMI prevention policies. For example, a risk prediction tool for individual patients could help doctors identify those most at risk and develop treatment strategies.
Considering AMI subtypes can also be effective. The researchers found that many traditional risk factors, including hypertension, diabetes and high cholesterol, are more common in type 1 AMI, while different AMI subtypes – including type 2 AMI (a subtype associated with higher mortality ) – are less common.
“We’re moving more toward a precision medicine approach, where we don’t treat every patient the same, but instead recognize that there are many different subtypes of AMI,” Lu said. “Interventions at the individual level are required to maximize health benefits and prevent AMI.”
The study is among the first and largest in the United States to comprehensively assess the associations between a broad spectrum of predisposing risk factors and incidents of AMI in young women and a comparable sample of young men. The study design also included a comparable population-based control group from the National Health and Nutrition Examination Survey, a program designed to assess demographic, socioeconomic, nutritional, and health-related information.
A longitudinal study is traditionally used to assess risk of AMI in younger populations. However, since the incidence rate in young people is low, it takes a long time for the disease to manifest itself. Therefore, researchers often don’t have enough AMI events to draw conclusions about risk factors and their relative importance in young women and men, Lu said.
“Here we used a novel study design with a large cohort of patients with AMI and then identified an age, sex and race matched population control from a national population survey to compare this and we used a case-control design to to assess the association of these risk factors in AMI,” said Lu. “This is one of the first and largest studies to comprehensively address this topic.”
In the United States, hospitalization rates for heart attacks have been declining over time, according to a study in the journal JAMA Cardiology.
“However, if you analyze the proportion of these patients by age, you will see that the proportion of younger people being hospitalized for a heart attack is increasing,” Lu said. “So there seems to be a general trend for AMI to occur earlier in life, making prevention of heart attacks particularly important in younger people.”
Younger women account for about 5% of all heart attacks that occur in the US each year. “That small percentage impacts a large number of people because so many AMIs occur in the United States each year,” she said. “Each year, approximately 40,000 AMI hospital admissions are made among young women, and heart disease is the leading cause of death in this age group.”
Lu stressed the importance of education. “When we talk about a heart attack in young women, people often aren’t aware of it,” she said. “If we can prevent women from having heart attacks, that will improve outcomes.”
Raising awareness of the incidence of heart attacks in younger women is an essential part of the strategy, she said. The next frontier in preventing cardiovascular disease in young women could be a better understanding of the role of women-related factors.
Previous studies have shown that factors related to women may be associated with the risk of heart attack, but there is limited data in women under 55 to look at other factors that specifically affect women and analyze whether this contributes to heart attack risk,” said you.
The study team also included Shu-Xia Li, Yutian Liu, Rachel P. Dreyer, Rohan Khera, Karthik Murugiah, Gail D’Onofrio, Erica S. Spatz, all from Yale; Fatima Rodriguez from Sandford University; Karol E. Watson from the University of California, Los Angeles; and Frederick A. Masoudi of Ascension Healthcare. The VIRGO study was funded by the US National Institutes of Health.