Article In Brief

An analysis of data from the National Inpatient Sample on pregnant and postpartum patients with acute ischemic stroke treated with mechanical thrombectomy suggests that endovascular therapy is a safe and efficacious treatment option for pregnant and postpartum people.

Endovascular mechanical thrombectomy (MT), an interventional procedure that removes a large blood clot from an artery or vein, is safe and effective for acute ischemic stroke (AIS) in pregnant and postpartum patients, according to a large population-based analysis published online first in the September 20 issue of Stroke.

After a series of landmark trials published in the New England Journal of Medicine in 2015, endovascular therapy has become a standard of treatment for AIS. However, it has not been evaluated in pregnant and postpartum patients, a group that is at increased risk but often excluded from clinical trials of interventional therapies.

Historically, pregnant patients are systemically excluded from clinical trials, so we felt it was important to report on this important subgroup of AIS patients. In prospective randomized controlled trials, MT has shown strong efficacy for the treatment of AIS with a number needed to treat of 2.6 for improved outcomes, senior study author Fawaz Al-Mufti, MD, associate chair of neurology for research and associate professor of neurology, neurosurgery, and radiology at New York Medical College, told Neurology Today.

Using data from the National Inpatient Sample, a database from the Healthcare Cost and Utilization Project, from 2012 to 2018, the authors analyzed data on pregnant and postpartum patients with AIS treated with MT. They compared them with nonpregnant patients treated with MT, and subsequently with pregnant and postpartum patients who were managed medically.

Compared to nonpregnant AIS patients treated with MT, pregnant patients experienced lower rates of intracranial hemorrhage and lower rate of poor functional outcome at discharge, Dr. Al-Mufti said. Our findings suggest that endovascular therapy is a safe and efficacious treatment option for pregnant and postpartum woman with AIS who are eligible. We hope providers as well as patients and their families can look to large database analyses such as our study to have the confidence to pursue this life-saving and deficit-preventing procedure should it otherwise be indicated.

The paper looked at 52,825 women hospitalized for AIS over a seven-year period, 4,590 of whom were pregnant or postpartum (defined as up to six weeks following childbirth). In this group, 180 women were treated with MT; these women tended to be younger (33 versus 71 mean years, p<0.001) and were more likely to present with extreme acute illness severity compared with the group of 48,055 nonpregnant patients treated with MT.

The study's primary clinical endpoints were functional outcome, all-cause in-hospital mortality, and hospital length of stay. Secondary endpoints included neurological complications specifically relevant to MT treatment for AIS, mainly intracranial hemorrhage and subsequent decompressive hemicraniectomy.

Patients treated with MT had lower rates of both intracranial hemorrhage (11 percent vs 24 percent, p=0.069) and poor functional outcome (50 percent vs 72 percent, p=0.003) at discharge. After adjusting for age, illness severity, and stroke severity, women who were pregnant or postpartum still showed an independently associated lower likelihood of developing intracranial hemorrhage (adjusted odds ratio, 0.26 [95% CI, 0.09-0.70]; p=0.008).

The authors also evaluated complications and outcomes between pregnant and postpartum patients treated with MT and those who were medically managed (4,410 patients). Using propensity score matching, the researchers reported pregnant and postpartum patients treated with thrombectomy had an increased rate (17 percent) of venous thromboembolism compared with medically managed pregnant and postpartum patients (0 percent; p=0.001) but a lower rate of pregnancy-related complications (44 percent vs 64 percent, p=0.034).They found no significant difference in postpartum complications, functional outcome at discharge, or hospital length of stay in these patient groups. No patients in the MT group experienced miscarriage after the procedure.

A major strength of the study, Dr. Al-Mufti said, was the large sample size using national data and, particularly, the number of pregnant and postpartum patients who had undergone MT. Although the retrospective nature of our finding is a limitation of the study that would normally warrant prospective validation, given the rarity of ischemic stroke during pregnancy and the postpartum period, prospective trials evaluating the usage of MT would be challenging.

As a result, he said, large-scale, multicenter investigations such as the present analysis offer meaningful insight into the utilization of these treatment modalities.

Vascular neurologists and neurocritical care experts told Neurology Today that this study was an important contribution to an area of stroke care that is insufficiently studied.

The current guidelines from the American Heart Association recommend consideration of these types of therapies including thrombolysis and endovascular MT during pregnancy if a person has disabling deficits and the benefits outweigh bleeding risks, but they make a slightly equivocal recommendation that it is reasonable to do it and don't really make recommendations about the postpartum period, said Eliza C. Miller, MD, assistant professor of neurology in the division of stroke and cerebrovascular disease at Columbia University Medical Center, who focuses on women's cerebrovascular health and cerebrovascular complications of pregnancy and the postpartum period.

This is mainly because there's really been a lack of data because pregnant and postpartum people have been excluded from all of the prospective trials that have looked at the safety and efficacy of these types of hyperacute stroke therapies.

The current paper presents the largest cohort reported to date of pregnant patients with AIS treated with MT, said Christa O'Hana S. Nobleza, MD, MSCI, medical director of the neurocritical care service at Baptist Memorial Hospital and associate professor in the department of neurology at the University of Tennessee Health Science Center in Memphis.

Before this study, there were only case reports or case series reporting on interventional acute stroke therapy for the pregnant. This study evaluated important factors that possibly limited pregnant patients from undergoing MT, such as potential for hemorrhage and worsening outcomes, and showed that those who underwent thrombectomy did not have higher rates of intracranial hemorrhage or worsened outcomes.

The data found an increased use of thrombectomy since the 2015 thrombectomy clinical trials and also showed that the outcomes from thrombectomy in pregnant women versus thrombectomy in nonpregnant women were similar or betterprobably because of the age difference in these two groups, Victor C. Urrutia, MD, FAHA, associate professor of neurology and director of the Comprehensive Stroke Center at the Johns Hopkins Hospital, said. In addition to the increase in thrombectomy, it shows there's a been a decrease in hemicraniectomy, suggesting that perhaps the benefit of thrombectomy, which is mainly decreasing the size of the stroke, has prevented the need of treatments of large stroke-producing edema in the form of hemicraniectomy.

One key takeaway is the group of women treated with MT didn't have pregnancy-related complications or increased mortalityso all of these things that people worry about did not occur, Dr. Miller said. Another interesting finding, she added, was that pregnant and postpartum patients who had MT were more likely to have venous thromboembolism. This could be explained by the fact that those who get MT are people who had a very large stroke, so you're possibly comparing them with people who had a more minor stroke and might be able to get up and walk more easily, she noted. But it is important for us to remember in general that pregnancy and the postpartum state increase the risk of venous thromboembolism very significantly, so just like with all our stroke patients, we must be hypervigilant about preventing this complication.

Overall, this paper establishes more conclusively that endovascular thrombectomy for acute stroke should be made available for pregnant women who meet the criteria, Dr. Urrutia said. I think the paper might change practice in the sense that those who may have been hesitant for lack of data to consider patients who were pregnant and who were having stroke for treatment might more easily consider it.

Dr. Miller agreed. Yes, there can be a discussion of risk, but I would say in the vast majority of cases, the benefits are going to be so much greater than the risks. I hope that this study helps reassure people that it's okay to offer this therapy that's so life- and function-saving.

The limitation of the analysis, as the study authors and all of the commentators pointed out, is its use of an administrative dataset, which does not allow for more nuanced information about the patients or their long-term outcomes beyond hospital discharge.

Still, Dr. Nobleza said she believes this study provides an important foundation for future potential studies analyzing the effect of acute stroke reperfusion therapies on pregnant patients. Study designs that can incorporate the pregnant patient are needed; however, they are challenging. For now, I believe the information from this study can still be utilized to guide shared decision making regarding acute stroke reperfusion therapy for the pregnant population.

Dr. Urrutia said he would also like to see more specific outcome data in future studies, for example, using measures like the modified Rankin score. I doubt that there would be a randomized clinical trial to test this, so I think the future is probably going to be more pooled individual patient data meta-analyses and those types of studies. With a relatively low frequency eventpregnancy-associated stroke treated with thrombectomy, the difficulty is to be able to get enough cases to also witness the more granular data.

Dr. Miller, however, suggested that the concept of excluding people who are pregnant or postpartum from clinical trials should be revisited. Stroke is a major cause of maternal mortality in the United Statesand even more a cause of severe maternal morbidityso we should be doing everything we can to prevent death and disability in people who are pregnant or postpartum.

While she acknowledged the challenging nature of designing such clinical trials, she pointed out that she conducts a lot of research in collaboration with obstetrician-gynecologists, who are experts in doing clinical trials in pregnant and postpartum people, including interventional and medication trials. There's a whole network for maternal fetal medicine trials, just like we have StrokeNet in stroke, and they do these trials all the time, so it's certainly feasible to enroll pregnant people in clinical trials.

Dr. Miller said it is frustrating to see people who happen to be pregnant or postpartum are not being treated for acute stroke in the same way they would be treated if they weren't pregnant. For example, I sometimes see or have heard about imaging being delayed because people are worried about the radiation risk and they wait for the MRI or they don't do the CT angiogram, but all of these things have been shown to have minimal risk in pregnancy, and the recommendations from both the American College of Obstetricians and Gynecologists and also the American College of Radiology state that, in the case of a life-threatening condition in the mother, these types of imaging studies should not be delayed or withheld. Obviously stroke with a large vessel occlusion is life-threatening and function-threatening, Dr. Miller said.

We should all remember that pregnant women and women in the early postpartum time, which is generally considered to be 6 weeks, are at higher risk of stroke than women of the same age and profile, and that we should address acute onset of neurologic deficits the same way that we would address any other person and consider the treatments that are appropriate depending on the cause of those deficits, Dr. Urrutia said.

Dr. Urrutia is the PI of a national randomized multisite trial called OPTIMISTmain, which is funded by Genentech. Dr. Miller receives research support from the National Institutes of Health, National Institute of Neurological Disorders and Stroke, and the Louis V. Gerstner, Jr. Foundation.

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