According to a new study pregnancy and related hormonal changes that continue 12 weeks after giving birth increase a woman's risk of heart attack. Although the likelihood of having a heart attack during pregnancy is very low - just 1 in every 16,000 deliveries - it is still 3 to 4 times higher than non-pregnant women of the same age.
Additionally, heart attacks during pregnancy tend to be more severe and lead to more complications, according to a study presented at the annual scientific sessions of the American College of Cardiology meeting in Chicago this week.
Hormonal changes, increased blood volume and other physiological changes that happen during pregnancy increase the risk, researchers said, adding that heart attacks happen for different reasons in pregnant women than those commonly seen in the general population. Atherosclerosis, a narrowing of the arteries, is the most common cause of heart attack in the general population, but this was the cause in only a third of pregnant women who had a heart attack, they said. The more common reason pregnant women had a heart attack was a condition called coronary dissection, a separation of the layers of the artery wall that blocks blood flow. They said this condition is very rare among non-pregnant patients.
This suggests that in at least some cases, the traditional approach to treating the condition during pregnancy and post partum may not always be best, researchers said. “We have very clear guidelines for (heart attack) in the general population. These guidelines, however, may not always apply to women with pregnancy-associated heart attacks and may actually cause more harm than good,” said Dr. Uri Elkayam a professor of medicine and obstetrics-gynecology of the University of Southern California in Los Angeles and the study's lead researcher.
An analysis of 150 cases taken since 2005 were added to the 228 cases taken prior to 2005 for the study. Researchers found that most pregnant women did not have traditional cardiovascular risk factors, such as high cholesterol, high blood pressure and diabetes. Yet their heart attacks were more severe and the death rate was 2 to 3 times higher than what is expected of non-pregnant women the same age. Heart attacks during pregnancy prove fatal for about 7% of women, a rate that's about three times higher than what doctors would expect in other women of the same age said Elkayam.
“These are big heart attacks,” Elkayam said, noting that women who survive are at high risk of complications, such as heart failure and shock. Giving these women a clot-busting drug — which normally helps patients — can actually make the artery tear even further. So can imaging the heart using another common test, called coronary angiography. In seven of 129 women, performing an angiography made the rupture worse. One of those women died, and another later died while waiting for a heart transplant. Four of the women needed immediate heart bypass surgery, he says.
When pregnant women come to the hospital with heart attack symptoms, “the biggest problem is that we honestly don't know what to do with them,” said Martha Gulati, director of preventive cardiology and women's cardiovascular health at Ohio State's Wexner Medical Center, who wasn't involved in the new study. “We don't even know how to advise them about whether they should try to get pregnant again.”
Given these dangers, Elkayam says doctors should try to evaluate patients non-invasively, such as through an EKG, which measures the heart's rhythm, and stress testing, which can involve running on a treadmill. If doctors feel they must insert a balloon into the artery to save a mother's life, they should do it as quickly and carefully as possible.
Because heart attacks in pregnant women and new moms are rare, hospitals may only treat a handful of patients a year, Gulati said. That's not enough for doctors to learn which treatments have the greatest success. Doctors at the Mayo Clinic are trying to gather data on these rare heart attacks through a registry, which allows specialists around the country to pool their findings, Gulati said.
Pregnancy can increase heart attack risk in several ways, said cardiologist Nieca Goldberg, medical director of NYU Langone Medical Center's Tisch Center for Women's Health. Pregnancy changes a woman's balance of hormones and makes her more prone to blood clots. Because of the increased demands of the fetus, her blood volume increases by 50%. And while the women in the study appeared largely healthy, Goldberg notes that 25% were smokers. Quitting smoking is one of the most important things women can do to protect themselves and the baby, Goldberg said.
A study published last month in the Journal of the American Medical Association found that, overall, women are much less likely to experience chest pain during heart attacks, making their conditions harder to recognize and treat, leading to a higher overall risk of death.
Seventy percent of spontaneous coronary dissections occur in women and 30 percent of those occur during pregnancy or immediately after, according to Dr. Sharon Hayes, a cardiologist at the Mayo clinic in Rochester, Minn. who was not involved in the study. ”We have known for decades that young women with heart attack have higher mortality than men at the same age and also have very different cardiovascular disease risk factors,” she said.