Younger women may be more likely to die in the decade following a heart attack than men of the same age, a new study suggests.
In general, women under age 50 experience fewer heart attacks than men in the same age range. The new study, published Oct. 13 in the European Heart Journal, also reflects this trend; of 2,100 heart attack patients treated at the Brigham and Women's Hospital and Massachusetts General Hospital in Boston between 2000 and 2016, only about 400 were women. The average age of all the patients in the study was 44 years old.
But over the long-term, these young women were more likely to die than young men. The study authors followed the patients for a median of 11 years, and found that women were 1.6 times more likely to die from any cause than men during that time.
"Notably, the differences in mortality in our study were primarily driven by non-cardiovascular death," meaning deaths not caused by a heart condition, study author Dr. Ersilia DeFilippis, a cardiology fellow at New York Presbyterian-Columbia University Irving Medical Center, told Live Science in an email. Examples of these non-cardiovascular causes of death included cancer and sepsis, a kind of overblown immune response to an infection.
Unfortunately, "there were no clear explanations as to why women had lower survival," DeFilippis noted, though the study revealed a number of factors that may be at play.
"The risk factors for disease of other organs overlap with risk factors for heart disease," Dr. Marysia Tweet, an assistant professor in Cardiovascular Medicine at the Mayo Clinic, who was not involved in the study, told Live Science in an email. "A heart attack and the ramifications of a heart attack may affect the health of other organs. Long-term mortality is likely due to a combination of multiple factors."
For instance, women in the study had higher rates of diabetes than the men, as well as higher rates of diseases such rheumatoid arthritis , where joint pain and inflammation are often triggered by an immune system attack. This persistent inflammation may drive the formation of fatty plaques in blood vessels, which can block arteries and lead to a heart attack, according to a 2012 report in the journal Arteriosclerosis, Thrombosis, and Vascular Biology. That same inflammation may also affect how patients recover.
In addition, the women showed higher rates of depression than men in the study. "Depression impacts adherence to healthy lifestyle recommendations and medications," which could impact women's long-term survival after a heart attack, Tweet wrote in a commentary also published in the European Heart Journal about the research. But it's also possible that the physiological changes that coincide with depression independently worsen outcomes; for instance, elevated levels of stress hormones and inflammatory molecules called cytokines could worsen a patient's prognosis, she wrote.
In general, women are about twice as likely as men to experience stress-induced reduction in blood flow to organs after a heart attack, according to a 2018 report published in the journal Circulation.
Beyond these risk factors, women also received different care from men when being treated for their heart attacks.
Women in the study were less likely than men to undergo coronary angiography, an exam in which dye is injected into the blood vessels so doctors can view those vessels and possible blockages on X-ray. They were also less likely to receive coronary revascularization, in which blood flow is restored through surgery or placement of a stent into the obstructed artery. When discharged from the hospital, women were less likely to be given medications like aspirin, beta-blockers, ACE inhibitors and statins, which are often prescribed after a heart attack to protect the organ from further damage.
These differences in medical care may reflect "persistent sex or gender disparities in clinical care and decision-making," or they may reflect clinical differences in how the men and women's heart attacks unfolded, Tweet wrote. For example, more women than men developed a spontaneous tear in an artery in the heart, which would deter doctors from performing an invasive procedure like coronary revascularization.
Women were also less likely to have severe blockages in their coronary arteries as compared with men, which would also reduce the need for coronary revascularization, Dr. Ron Blankstein, a professor of medicine at Harvard Medical School and a preventive cardiologist at Brigham and Women's Hospital, wrote in a statement.
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Socioeconomic status may be another critical factor in women's long-term survival rates, the authors wrote. "In our study, we found that women had lower median incomes than men and were more likely to have public insurance," DeFilippis said. "Therefore, there are likely differences in access to care which are playing a role."
Further studies will be needed to tease out how these factors affect women's long-term survival after a heart attack, the authors noted. In the meantime, cardiologists "need to educate women regarding the risks of cardiovascular disease and potential worrisome symptoms," DeFilippis said. In the study, chest pain was the most commonly reported symptom among both men and women, but a higher proportion of women reported symptoms like shortness of breath, heart palpitations and fatigue.
Doctors can improve women's care by recruiting more women into clinical trials, actively including sex-based data in studies of heart attacks and better addressing sex-specific risk factors when educating patients, Tweet wrote in her commentary. For instance, gestational diabetes and preeclampsia — severely high blood pressure during pregnancy — can place women at higher risk for heart attacks, she wrote. Ovary removal has also been associated with a higher risk of heart attacks, potentially because ovaries produce the sex hormone estrogen, which is thought to protect against heart disease, according to Harvard Health.
Furthermore, some research suggests that women face greater cardiovascular risks from smoking than men do; all these risk factors warrant further study, especially in terms of whether the risk they present outmatches the protective power of estrogen and leaves women more prone to heart attacks, the authors wrote.
Originally published on Live Science.