Black women at increased risk for weakened heart muscle at childbirth

Black women are at significantly increased risk for developing a potentially deadly weakening of the heart muscle around the time of childbirth, researchers report.

A study examining the incidence of peripartum cardiomyopathy in women who gave birth at a Medical College of Georgia's teaching hospital between July 2003 and July 2008, showed that while 55 percent of the women were white, 93 percent of those who developed cardiomyopathy were black, said Dr. Mindy B. Gentry, an MCG cardiologist.

"When it hits, it's totally unexpected because these are young, otherwise healthy women with young children. (They aren't patients) you'd expect to have any sort of health problem much less heart failure," Dr. Gentry said.

Other risk factors include hypertension, being unmarried, smoking during pregnancy and having more than two previous pregnancies, but African-American race was the most important predictor, said Dr. Gentry, corresponding author on the study published in the Journal of the American College of Cardiology.

Two previously published studies from Haiti and South Africa found a higher incidence of peripartum cardiomyopathy than in other parts of the world but essentially all the participants were black. The heterogeneous population giving birth at MCGHealth Medical Center made it easier to assess the effect of race, Dr. Gentry noted.

Further research is needed to identify potential environmental and/or genetic factors associated with African descent that explain the increased risk, the researchers said. They have begun follow up studies looking for any racial differences in healthy hearts following delivery, such as how much blood is ejected with each beat.

Peripartum cardiomyopathy typically occurs in the last month of pregnancy or the first few months after delivery. Symptoms include shortness of breath, particularly when lying down, as excess fluid congests the lungs and the rest of the body. The suffocating backlog is caused by an enlarged, stiff heart muscle that no longer pumps efficiently.

Drugs can improve pumping efficiency. About half the time, the condition spontaneously reverses but it can cause debilitation and death, with mortality rates ranging from 15-56 percent. Of the 28 women with peripartum cardiomyopathy in the MCG study, one patient died and another required a heart transplant.

In every pregnancy, the blood volume increases about 50 percent to accommodate increased demands from the placenta and baby. Heart rate increases to help circulate the extra blood, Dr. Gentry said. Black women also are at increased risk for abnormal increases in blood pressure, called preeclampsia, that can occur late in pregnancy.

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