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Physically removing a blood clot in the brain is a safe and effective treatment for pregnant women having a stroke, a new study by several New York Medical College (NYMC) faculty, residents and students suggests.

Stroke during pregnancy is rare, but the risk increases during pregnancy and for up to 12 weeks after giving birth, or postpartum. The most common type is ischemic stroke, where a clot blocks blood flow in the brain. Mechanical thrombectomy – where a surgeon threads a catheter through an artery to remove a large clot – became a standard treatment in 2015 after a series of landmark studies.

"Unfortunately, pregnant and postpartum patients are systemically excluded from many clinical trials," said Fawaz Al-Mufti, M.D., assistant professor of neurology, neurosurgery and of radiology and senior author of the new study, published in the American Heart Association journal Stroke.

NYMC faculty and resident authors on the study also included Alis J. Dicpinigaitis, SOM Class of 2023, Tolga Sursal, M.D., neurosurgery resident, Catherine A. Morse, SOM Class of 2023, Camille Briskin, SOM Class of 2023, Christeena Kurian, M.D., clinical assistant professor of neurology, Gurmeen Kaur, M.D., assistant professor of neurology and neurosurgery, Ramandeep Sahni, M.D., clinical associate professor of neurology, Chirag D. Gandhi, M.D., chair of Department of Neurosurgery and professor of neurosurgery, neurology and of radiology.

The rarity of such strokes also poses a challenge for researchers, with an estimated 1.5 to 67.1 strokes per 100,000 deliveries – or as little as 0.0015% of pregnant women. So, Dr. Al-Mufti, and his fellow researchers turned to big data. They used a database called the National Inpatient Sample to identify 52,825 women hospitalized with strokes between 2012 and 2018. Of those women, 4,590 were pregnant or had just given birth. And of those women, 180 had been treated with mechanical thrombectomy.

The study first compared those 180 pregnant or postpartum women with 48,055 non-pregnant women who also had a mechanical thrombectomy. After the procedure, the pregnant group was less likely to have dangerous bleeding inside the skull, called intracranial hemorrhage.

The pregnant/postpartum women also did better overall after thrombectomy. Half had moderate to severe disability when they were discharged, compared to nearly three-quarters of the group that was not pregnant. None of the pregnant/postpartum women died in the hospital; 14% of the non-pregnant group did.

The pregnant women tended to be younger, with an average age of 33, compared to 71 for the larger non-pregnant group. But the pregnant women were more likely to have had more severe strokes.

The study also compared pregnant women who had mechanical thrombectomy with 4,410 pregnant or postpartum women who had their strokes treated medically – such as with clot-dissolving medication, Al-Mufti said. This analysis involved selectively matching women whose situations were as similar as possible, although researchers said they lacked data on race.

In this comparison, both groups were similar in their rates of intracranial hemorrhage and post-birth complications and in how well they could function when they left the hospital. Pregnancy complications were less common after mechanical thrombectomy than medical management (44% versus 64%), and no one in the thrombectomy group experienced miscarriage.

The mechanical thrombectomy group did have a higher rate of dangerous blood clots in large veins, often in the legs, called deep vein thrombosis, or in the lungs, called pulmonary embolism.

Al-Mufti said this could be because those patients have longer hospital stays, and immobility can lead to such clotting. Or it could be the women in this group were predisposed to intense clotting and more severe strokes, he said. "I don't believe that there was a causation here, simply a correlation."

Al-Mufti said the study suggests pregnant stroke patients should be monitored carefully for blood clots as they recover. And overall, it tells doctors they should not be wary about using mechanical thrombectomy in pregnant women. "Quite the contrary, endovascular therapy can be very efficacious and very helpful in this patient population."

Excerpted from a September 2021 article published by American Heart Association News.