Nifedipine Seen Risky in Pregnant Women With Heart Conditions

Certain pregnant women with the cardiac condition aortic stenosis may be at risk of hypotension and chest pain from nifedipine, the preferred drug to prevent premature labor, according to a case report.

Clinicians should potentially order echocardiography for pregnant women with aortic stenosis, which can cause chest pain, fainting, and heart failure, and when a woman has signs and symptoms consistent with aortic stenosis, another drug other than nifedipine should be used to prevent premature labor, reported Cullen Soares, MD, and Michael Gilson, MD, both of the Warren Alpert Medical School at Brown University in Providence, Rhode Island.

While heart failure is rare in pregnant women with aortic stenosis, "the hemodynamic changes that accompany late-term pregnancy make these women particularly sensitive to the vasodilation caused by nifedipine," they argued in the Annals of Internal Medicine.

They presented the case of a woman, age 31, with a twin pregnancy, who had a successful intrauterine ablation procedure at 18 weeks gestation. She was described as having "severe stenosis of the bicuspid aortic valve," but no other risk factors for vascular disease. Following the procedure, the authors said she was given the standard prophylaxis for tocolysis, or premature labor.

The patient developed hypotension with the hour and chest pain "with diffuse ST-segment depressions on electrocardiogram." She was then treated with intravenous phenylephrine, which is indicated to increase blood pressure in adults with clinically significant hypotension, and transferred to the cardiac care unit where the patient was evaluated and phenylephrine was withdrawn.

The patient was then treated with norepinephrine ("to provide better blood pressure support") and calcium gluconate ("to reverse the effects of nifedipine"). After she was stable, she was given indomethacin, another agent which can prevent premature labor, in place of the nifedipine, the authors said.

"Nifedipine for tocolysis is commonly used and generally well tolerated in healthy women. However, there is a lack of data about its use in twin pregnancies, and recommendations advise cautious use in patients with cardiovascular dysfunction," they wrote. "Nifedipine for tocolysis has been reported to cause severe maternal hypotension leading to fetal death, but not enough is known about the frequency of these adverse events."

As such, the authors concluded that clinicians should order echocardiography, as well as avoid use of nifedipine to prevent premature labor in women with "historical or physical examination findings" that suggest aortic stenosis.