Study: Pregnancy Increases Fatal Heart Attack Risk
March 28, 2012

Study: Pregnancy Increases Fatal Heart Attack Risk

Pregnancy raises the risk of fatal heart attacks, even in healthy women without risk factors for heart disease, a new study finds.

Furthermore, heart attacks during pregnancy tend to be more severe, lead to more complications, and also occur for different reasons than commonly seen in the non-pregnant general population, suggesting that, in some cases, the standard approach to managing this condition may not always be best, according to research presented Sunday at the American College of Cardiology's 61st Annual Scientific Session.

While the chance 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, the researchers said.

The changes brought about by pregnancy, including the dramatic shift in hormones and increased volume of blood being pumped through the body, can increase a woman's risk of heart attack during pregnancy and in the 12 weeks after delivery.

There is limited clinical information about how to optimally treat–and how not to treat–heart attacks during pregnancy and post partum.

The current study, which extends two previous surveys by the same research group, analyzed 150 new cases of heart attacks associated with pregnancy occurring since 2005 to better understand how heart attacks in pregnant women occur and are treated.

The analysis found that most pregnant women did not present with conventional cardiovascular risk factors, such as high blood pressure, diabetes or high cholesterol levels, yet they tended to have more serious heart attacks.

In fact, the death rate in these women was 7 percent -- two to three times higher -- than what is expected in non-pregnant patients of the same age.

Furthermore, heart attacks in most of these women were caused by different mechanisms than those occurring in the non-pregnant general population, the researchers said.

"Despite advances in the management of myocardial infarction, we found that the rate of severe complications including heart failure, cardiogenic shock, and maternal or fetal mortality continues to be high among pregnant women compared to others," said Uri Elkayam, MD, professor of medicine at the University of Southern California in Los Angeles and the study's lead investigator.

"Therefore, every effort should be made for early diagnosis and appropriate treatment of pregnancy-associated acute myocardial infarction. We believe this study provides important information that can help guide clinicians, and hopefully improve the care of these patients."

While atherosclerosis–or a narrowing of the arteries due to fatty build-up–is the most common cause of heart attacks in the general population, this was only the cause in one-third of pregnant women.

More common among pregnant women was coronary dissection, a separation of the layers of the artery wall that blocks normal blood flow, something highly rare among non-pregnant patients.  The condition is believed to occur during and immediately after pregnancy because of the weakening of the wall of the coronary arteries.

Researchers also found that coronary dissection may actually be worsened by blind use of guideline-recommended standard therapies such as thrombolytic therapy.

"We have very clear guidelines for treating myocardial infarction 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. Elkayam.

"It is, therefore, important to identify the cause of heart attack in pregnant women before deciding what therapies to use."

In particular, coronary angiography to identify the mechanism of heart attack and guide therapy is recommended in high-risk patients when urgent treatment is needed, he said.  At the same time, however, in several patients coronary dissection was reportedly caused by coronary angiography or angioplasty and led to either death, a need for extensive stenting or coronary bypass surgery.

For this reason, Dr. Elkayam advises that stable and low-risk women with pregnancy-associated heart attack be treated conservatively.

"This study is another step in better understanding the cause of pregnancy-associated heart attacks and their potential management," said Dr. Elkayam, adding that as more women postpone having a first baby, the number of pregnancy-associated heart attacks is expected to grow.

He said he is hopeful that a national registry will be created to better track heart attacks in pregnant women, and that optimal protocols that lead to better outcomes will be established.