Pregnancy and Heart Disease

Heart attacks are often linked to high blood pressure, diabetes and smoking. But a new study suggests pregnancy can also increase the risk.

"There are significant hormonal changes that occur during pregnancy that affect the coronary arteries," said study author Dr. Uri Elkayam, professor of medicine, cardiology, and obstetrics and gynecology at the University of Southern California.

Heart attacks are usually triggered by atherosclerosis — a build-up of plaque that narrows the arteries and makes it harder for blood to flow.  But only a third of heart attacks that occur during pregnancy are caused by atherosclerosis, Elkayam said. Rather the vast majority are caused by a tear of one of the three layers that make up a blood vessel known as a dissection.

Seventy percent of spontaneous coronary dissections occur in women and 30 percent of those occur during pregnancy or immediately after, according to Dr. Sharonne 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.

Heart attacks are usually treated with clot-busting drugs and balloons or stents that open up the narrowed artery. But for pregnant women with dissections, typical treatments can make the situation significantly worse.

Prepregnancy Cardiovascular Risk Factors
Over the past decade, birth rates for older women (age 25 to 44 years) have increased. Older women have a higher prevalence of traditional cardiovascular risk factors, such as diabetes and chronic hypertension, and of preexistent cardiovascular disease than younger women. The impact of preexisting cardiovascular risk factors on the mother and fetus are profound. Traditional risk factors, such as smoking, diabetes, hypertension, hyperlipidemia, and thrombophilia, are associated with increased risks of spontaneous abortion, maternal placental syndromes (see next section), preterm labor or premature rupture of membranes, and acute arterial or venous thromboses during pregnancy. Furthermore, the presence of such risk factors also predicts the future development of coronary artery disease, chronic hypertension, stroke, and peripheral arterial disease in the mother.

 

Emerging risk factors for future cardiovascular disease in women include maternal obesity and gestational diabetes. Maternal obesity and morbid obesity are associated with increased risks for gestational hypertension, preeclampsia, gestational diabetes, and fetal birth weight of more than 4000 g. 5 Gestational diabetes can progress to the development of type 2 diabetes. Although the reported incidence of type 2 diabetes in women with gestational diabetes varies widely, the cumulative incidence of type 2 diabetes appears to increase markedly in the first 5 years after pregnancy.

 

Cardiac diseases complicate 1% to 4% of pregnancies in women without preexisting cardiac abnormalities. A working knowledge of the normal physiology of pregnancy is often helpful in the management of patients with heart disease. Patients with preexisting cardiac lesions should be counseled in advance about the risk of pregnancy. Familiarity with the treatment of commonly encountered cardiac diseases during pregnancy is becoming increasingly important for internists and cardiologists as they join the team of obstetricians and anesthesiologists in the care of these complicated patients.

A heart attack occurring in a young, previously healthy young woman is very unusual, with a reported incidence of 1/16,000. Elkayam emphasized that "women should not be afraid to become pregnant because the incidence of a heart attack is very small."