Even though coronary artery disease (CAD) affects as many women as men, high-risk women are less likely to receive preventative treatments like statin medications or lifestyle advice, less likely to receive rehabilitation after a heart attack, and more likely to die from one. That's the conclusion of a new review paper published in Global Heart examining more than a hundred studies on CAD.

According to the American Heart Association, CAD is the leading cause of death in the United States for both men and women. But more women than men die of CAD, and more women have died of CAD than of cancer, respiratory disease, Alzheimer’s disease, and accidents combined.

“For far too long, many believed that coronary artery disease was primarily a ‘man’s disease,’” say the authors, Dr. Kavita Sharma and Dr. Martha Gulati of Ohio State University. “With increased awareness of the fact that the leading cause of death in women is CAD, this notion is slowly eroding.”

Perhaps not fast enough. A 2004 study found that fewer than one in five doctors knew that more women die from CAD than men each year. “CAD’s impact on women traditionally has been underappreciated due to higher rates at younger ages in men,” explain the study authors.

And this affects how doctors treat their patients. Studies have found that women who go to the hospital with chest pain or other urgent heart symptoms are less likely to receive blood thinners and less likely to undergo cardiac catheterization. Women with heart symptoms were also less likely to be given early aspirin, beta-blockers, or timely treatment to restore blood flow through blocked arteries.

Later Onset, Worse Outcomes for Women

Women with CAD tend to develop the disease about 10 years later in life than men do, but the consequences are worse. Women under 50 who have a heart attack are twice as likely to die, and women over 65 are more likely than men to die in the first year after having a heart attack.

Can differences in treatment explain this difference in outcomes? The picture isn’t so clear, Sharma and Gulati found, because coronary artery disease appears to develop differently in women than it does in men.

The classical pattern of CAD in men usually involves cholesterol buildup on the walls of the main arteries that send blood to the heart, partially blocking blood flow. But more than half of women with non-obstructive CAD have chest pain and undergo repeat hospitalizations. 

When the researchers took a closer look, they discovered that women are much more likely to have diseased microvasculature, the web of tiny blood vessels that disperses blood from large arteries to nearby tissues. In men, heart attacks happened because an artery was blocked outright. In women, the heart muscle itself was slowly starved for oxygen until it failed.

Spot the Differences Between Men and Women

These differences in the development of heart disease suggest that both risk factors and treatment for CAD may differ between men and women.

As with men, CAD in women is affected by genetic and lifestyle factors: age, family history of heart disease, diabetes, obesity, high cholesterol, high blood pressure, smoking, and lack of exercise. 

But how these factors predict CAD differs by gender. After age 60, CAD cases in men increase at a regular rate, while in women the rate increases exponentially. Moreover, diabetes increases a woman’s risk of developing CAD three- to seven-fold, but only increases a man’s risk two- to three-fold.

Women can also develop CAD as the result of conditions that do not or rarely affect men. For example, autoimmune diseases are far more common in women. One type of autoimmune disease, systemic lupus erythematosus, causes a 50-fold increase in the prevalence of CAD. 

Women also undergo hormonal changes that men don't. Polycystic ovarian syndrome (PCOS) and the early age of a woman's first period both increased the risk of CAD later in life. This effect remained even after researchers controlled for a woman's weight. Women with breast cancer also experienced higher rates of CAD, though whether this is from the cancer or from hormonal treatments for it is unclear. Pregnant women also have additional risks, since preeclampsia and gestational diabetes both increase the likelihood of future CAD.

Now that the development of CAD in women is better understood, doctors can tailor treatments to female patients that specifically address microvasculature disease. Statins, beta-blockers, l-arginine, and a new drug called ranolazine can reduce CAD risk and symptoms.

However, much work remains to be done to raise the visibility of heart disease in women, expand treatment, and prevent unnecessary deaths.

You can find a full list of the American Heart Association’s risk recommendations here.

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