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Many people who suffer heart attacks early in life have low HDL cholesterol, researchers say.

Amanda MacMillan
March 13, 2017

While the rate of heart attacks in the United States has gone down in recent years, studies show it’s remained steady in people 50 and under. Now, new research suggests that many young heart attack victims have an unexpected risk factor in common: relatively normal levels of LDL “bad” cholesterol, but surprisingly low HDL “good” cholesterol.

Abnormal cholesterol is a known risk factor for heart disease, but doctors usually worry more about high numbers—both LDL and total cholesterol—than low ones. LDL cholesterol is associated with artery-clogging plaque, while HDL plays a role in clearing LDL from the arteries, reducing inflammation, and preventing blood clots.

Not much is known about the cholesterol profiles of younger people who have heart attacks, however. To investigate, Harvard researchers combed through 16 years of medical records at two large hospitals and identified 813 men under 45 and women under 50 who had been treated for a heart attack. (The average age for heart attack in the U.S. is 65 for men and 70 for women.)

The researchers were surprised to discover that the most common abnormality among these patients—occurring in 90% of men and 75% of women—was low HDL. Their finding suggests that low HDL should be considered an indicator of increased heart attack risk, says lead author Bradley Collins, a fourth-year student at Harvard Medical School, particularly in younger patients.

The findings also suggest that traditional tools may underestimate heart attack risk in this group by putting too much emphasis on age, Collins adds. Ultimately, he says, his team would like to develop new methods of assessing risk that better apply to younger people.

Collins and his team also found that heart attacks before age 50 may be especially dangerous for women, who had a higher rate of death from any cause than men in the study. They were also more likely to have had what’s known as a Type 2 heart attack, which is caused by something other than a blocked artery.

The new research will be presented on Friday at the American College of Cardiology's 66th Annual Scientific Session. It has not yet been published in a peer-reviewed journal.

RELATED: Heart Attack Signs Every Woman Should Know

The American Heart Association recommends that adults have their cholesterol checked every five years. Doctors use these readings—along with other factors, like age and blood pressure—to assess patients’ risk of heart disease.

“Our findings suggest that if physicians notice a low HDL-C in a patient, this patient may be at increased cardiovascular risk and may benefit from the institution of greater preventive methods,” Collins told Health in an email. “These include lifestyle changes such as smoking cessation, increased exercise, and better glucose and blood pressure control.” 

People with low HDL should also avoid foods high in trans fat, as these have been shown to raise LDL and also decrease HDL. Instead, they should focus on eating more monounsaturated and polyunsaturated fats—found in nuts, olive oil, and avocado. "These interventions can increase HDL-C, and improve overall cardiovascular health," says Collins. In some cases, he adds, doctors may also recommend medication to lower overall cholesterol.

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Collins says it’s important for people under 50 to make sure their doctor has an accurate cholesterol reading for them, and to take any medications they’ve been prescribed for heart health. According to a recent editorial in JAMA Cardiology, a disproportionate number of young patients with high LDL cholesterol—50%—do not take their prescribed statins.

Finally, says Collins, young people should learn as much as they can about their family’s heart-health history. If you have relatives who have had premature cardiac events—before age 55 in men and before age 65 in women—it’s likely that you’re increased risk yourself, and your doctor may want to monitor you more closely than normal.