Overall, acute myocardial infarction remains rare in women of childbearing age, but the prevalence is expected to rise as more women postpone pregnancy, according to a review of 103 women who had acute myocardial infarctions during pregnancy.
Coronary dissection was the cause of AMI in more than a quarter of the cases. A total of 28 patients (27%) had 41 dissected coronary arteries, even though this condition is rare as a cause of AMI in nonpregnant patients, according to the investigators, Dr. Arie Roth of Tel Aviv University and Dr. Uri Elkayam of the University of Southern California, Los Angeles.
“The coronary dissection is unique to pregnancy,” Dr. Elkayam said. “That means when a pregnant woman has acute MI, the clinician has to consider that many [of these women] would not have the usual atherosclerotic disease.”
It's important to define the nature of the MI by angiography before deciding on an aggressive therapy, and to avoid the automatic use of thrombolytic therapy, he said.
“Most physicians don't see patients like this or they see one in their lifetime, and it is difficult to know what to do, and so the patients may not get the appropriate care,” Dr. Elkayam said.
The physicians conducted this review of cases between 1995 and 2005 to update characteristics of AMIs during pregnancy from their 1995 analysis of 125 women who had AMIs during pregnancy between 1922 and 1995.
In the current review, the women's ages ranged from 19 to 44 years, but 72% were older than 30 years. The average age for women in both study groups was 33 years (J. Am. Coll. Cardiol. 2008;52:171–80).
“The diagnostic and therapeutic changes have been revolutionary,” Dr. Elkayam noted. For example, data on the coronary anatomy were available for only 54% of the early group, compared with 93% of the current group, a statistically significant difference.
Consequently, the approach is more aggressive in terms of performing angiography and angioplasty and placing stents in young women, said Dr. Elkayam, director of the heart failure program and a professor of ob.gyn. and medicine at the University of Southern California, Los Angeles.
Advances in technology helped to reduce the mortality rate from 21% in the earlier review to 11% in the current review. Although this difference was not statistically significant, it supports findings of reduced mortality rates from other studies and suggests “a significant improvement in the outcome of pregnancy-related AMI in the last decade,” the investigators noted.
The fetal mortality rate in the current study group was 9%, and two pregnancies were terminated because of concerns about drug teratogenicity.
Despite the relatively young ages of the women studied, risk factors for AMI were fairly common. Overall, 45% of the women were smokers, 24% had hyperlipidemia, 22% had family history of MI, 15% had high blood pressure, and 11% had diabetes.
“The incidence of MI in pregnancy is very low, but it was surprising that the risk factors were high,” noted Dr. Elkayam. Many younger women may not recognize risk factors such as a family history of MI or receive treatment for risk factors such as high cholesterol, or high blood pressure prior to pregnancy, he said.
Treating MI risk factors in pregnant women remains a challenge because the drugs that clinicians use are potentially risky to the mother, fetus, or both.
“Pregnant women are always excluded from trials,” Dr. Elkayam said. “So we are somewhat limited and we must consider true benefit vs. potential risk.”
Because physicians are treating two patients—mother and fetus—they need to make medication decisions wisely. “Sometimes we may have to use the therapy if the patient is at high risk,” he said.
It is difficult to conduct research with pregnant women, Dr. Elkayam acknowledged. But physicians must continue to report data from cases of acute MI in pregnancy in order to build a knowledge base to help manage these patients.
“We need to continue to follow these patients and perhaps start a registry so we can increase our understanding. For example, there are no data on the use of drug-eluting stents in pregnant women.”
Several techniques for evaluating possible AMI in nonpregnant patients are safe for pregnant women, with modifications as necessary based on concerns for fetal safety and factors associated with normal pregnancy. Safe choices include an echocardiogram and exercise testing, but radiation exposure should be limited, the investigators noted.
AMI in pregnant women is often overlooked or dismissed as reflux or indigestion, which can lead to a delay in diagnosis, Dr. Carole Warnes, a cardiologist at the Mayo Clinic, Rochester, Minn., said in an interview.