A recent study, published in Circulation: Cardiovascular Quality and Outcomes, confirmed that sex disparity in heart attack treatment is a global challenge. The study, which aimed to identify systemic causes for the problem, failed to find a smoking gun. Instead, the research showed that when it comes to myocardial infarction, women are getting the short end of the stick in every country studied. The researchers analyzed data from across the Americas, Europe, the Middle East and Asia. They examined medical records of over 1.5 million adults hospitalized for heart attack in six high-income countries between 2011 and 2018. In all six countries, doctors were less likely to give women crucial cardiac procedures to open blocked arteries within 90 days of hospitalization.
The researchers also uncovered a troubling trend in mortality rates. Women were more likely than men to die with a month of the most severe heart attack. These are clinically described as ST-elevation myocardial infarction (STEMI).
While some variation existed among countries, the overarching pattern suggests a significant issue in women’s health care after a heart attack. The disparities persisted for the duration of the study, suggesting the causes underlying the discrepancy are deeply entrenched.
Casting a Global Net
Women tend to have heart attacks at an older age than men. This is in part because circulating estrogen protects women against heart disease until they reach menopause. After age 65, however, heart disease becomes a leading cause of death in women. Despite this, American women have, historically, been less likely than men to receive procedures to open blocked cardiac blood vessels after a heart attack. American researchers have not been able to explain this difference in approach to women. Some suggestions include:
- Under-recognition by health care providers who mistakenly believe that women are “protected” against heart disease.
- Differences in typical heart attack symptoms for women and men.
- Biases and cultural attitudes towards women’s health
One approach to solving this mystery is to look at similar countries with different health funding models, age demographics, and cultural attitudes to gender. This allows researchers to compare and contrast broadly similar countries to find out where the differences in outcomes originate. A research team led by Peter Cram, MD, University of Texas, set out to determine whether gender differences in hospital care after a heart attack were distinct across countries. They aimed to pin-point underlying reasons for the disparity.
Researchers collected administrative data from more than 1.5 million adults, aged 66 years and over, hospitalized with a heart attack between 2011 and 2018. The team included six countries in the study: the United States, Canada, England, the Netherlands, Taiwan, and Israel. They compared male and female patients in each country quantifying: rates of admission to hospital, how likely they were to undergo a cardiac procedure or surgery within 90 days of hospitalization, and how likely they were to die within 30 days of their heart attack.
Gender Gap Maintained Across Borders
In all countries doctors were less likely to perform heart procedures, such as cardiac catheterization or cardiac bypass grafting, on women, within 90 days of hospitalization. The lone exception to this was Taiwan. In 2018, Taiwanese hospitals reported that women were slightly more likely than men (0.6%) to undergo bypass after a severe heart attack (STEMI).
The difference in treatment rates between women and men varied by procedure and country. Overall, the percentage of women treated to reopen blocked cardiac arteries ranged from 3% to 9% lower than men. The researchers noted that the largest gender gaps occurred in Israel, England, and the US. The discrepancy in outcomes largely stayed the same or increased over the course of the study. This seems to indicate that out-of-pocket cost or access to medical insurance is not responsible for the difference between procedures hospitals offer to men and women. The US and Israel provide hybrid health insurance systems with a mix of single payer and insurance for people over retirement age. In England health care is free at the point of delivery across all ages.
Changing the Game
Interestingly, in the US, the disparity in treatment rates for women after STEMI declined over the duration of the study. Worryingly, the gender gap increased for less severe heart attacks, known as NSTEMI. This indicates some change in training or education might have improved their ability to recognize a severe heart attack. Perhaps clinical guidelines as to what procedures should be offered to women were revised.
Overall, women with STEMI had slightly higher 30-day mortality rates compared to men in most countries across the seven-year period. On the other hand, with the exception of the US, women with NSTEMI tended to have lower mortality rates than men. These findings suggest a consistent global pattern, with women generally receiving fewer cardiac interventions. Further, women are more likely to die after a severe heart attack than men.
Trends Over Time
While this study suggests that women fare worse after a heart attack, encouragingly, the evidence is that women are having fewer heart attacks overall.
Between 2011 and 2018, the study found that hospitalization rates after heart attack decreased for both sexes, but the decrease was more significant for women. This has resulted in the hospital population of heart attack patients becoming more predominantly male over time. This trend appeared in all six countries studied, surprising the research team and raising questions about the cause.
“We really need to understand why heart attacks are becoming increasingly ‘male’ across all six countries.” Said Dr. Cram, in an interview with Medical News Bulletin. “Heart attacks have always been more common among men than among women and it seems that this is actually increasing. We need to know why.”
Heart attack rates have been declining in developed nations for both genders since the 1970s. Why this trend might be more pronounced in women is a mystery. It’s possible that women tend to be better at taking care of themselves. For example, women might be more likely to eat a healthy diet, be more physically active and less likely to smoke. It is also feasible that women now have better access to perimenopausal hormone replacement therapy. Some research implicates HRT in reducing the incidence of cardiovascular disease and heart attack in women.
Better MI Awareness Is Needed
The study highlights the need for better public understanding of heart attack risk. “Both women and men [need] to realize that anyone can have a heart attack—women and men,” says lead author Dr. Peter Cram. “Husbands and sons need to be aware that wives, mothers, sisters, co-workers who are women can have heart attacks just like men.”
The authors also point out that health care providers (doctors, nurses, and paramedics) need to ensure they are treating all patients according to the best available evidence. “We should constantly be looking at our own data to examine whether there might be differences in how we treat different patient populations (by sex, by race/ethnicity, by gender, by socioeconomic status, etc.),” says Cram. “When we see differences we need to really dig into them and make changes in our treatment protocols when indicated.”
References
Javed A, Ravi PC, Bilal Delvi S, et al. The Relationship Between Myocardial Infarction and Estrogen Use: A Literature Review. Cureus. 2023;15(9):e46134. doi:10.7759/cureus.46134
ICES | Sex-based disparities in acute myocardial infarction treatment patterns and outcomes in older adults hospitalized across 6 high-income countries: an analysis from the international health systems research collaborative. ICES. Accessed April 11, 2024. https://www.ices.on.ca/publications/journal-articles/sex-based-disparities-in-acute-myocardial-infarction-treatment-patterns-and-outcomes-in-older-adults-hospitalized-across-6-high-income-countries-an-analysis-from-the-international-health-systems-rese/
Lu H, Hatfield LA, Al-Azazi S, et al. Sex-Based Disparities in Acute Myocardial Infarction Treatment Patterns and Outcomes in Older Adults Hospitalized Across 6 High-Income Countries: An Analysis From the International Health Systems Research Collaborative. Circulation: Cardiovascular Quality and Outcomes. 2024;17(3):e010144. doi:10.1161/CIRCOUTCOMES.123.010144
Maas AHEM, Appelman YEA. Gender differences in coronary heart disease. Neth Heart J. 2010;18(12):598-602. doi:10.1007/s12471-010-0841-y
Mensah GA, Wei GS, Sorlie PD, et al. Decline in Cardiovascular Mortality. Circulation Research. 2017;120(2):366-380. doi:10.1161/CIRCRESAHA.116.309115
