Stroke Alert: A Review of Current Clinical Stroke Literature

By Dara Jamieson, MD, Associate Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Jamieson reports that she is a retained consultant for Boehringer Ingelheim, Merck, and Ortho-McNeil, and is on the speakers bureau for Boehringer Ingelheim.

Hypertension and the Pregnant Woman: An Increasing Risk for Stroke Now and in the Future

Synopsis: The incidence of stroke associated with pregnancy, especially cerebral venous sinus thrombosis, is increasing, with hypertension as a major culprit. Hypertension as a complication of pregnancy increases a woman's risk of stroke in the future.

Sources: Kuklina EV, et al. Trends in pregnancy hospitalizations that included a stroke in the United States from 1994 to 2007: Reasons for concern? Stroke 2011; Jul 28. [Epub ahead of print] Wasay M, et al. Predictors of cerebral venous thrombosis and arterial ischemic stroke in young Asian Women. J Stroke Cerebrovasc Dis 2011; Apr 19. [Epub ahead of print] Wang I-K, et al. Hypertensive disorders in pregnancy and preterm delivery and subsequent stroke in Asian women: A retrospective cohort study. Stroke 2011;42:716-721.

The report of kuklina et al analyzed stroke hospitalizations for women in the antenatal, delivery, and postpartum periods from 1994-1995 and from 2006-2007. Hospital discharge data were obtained from the Nationwide Inpatient Sample, developed as part of the Healthcare Cost and Utilization Project sponsored by the Agency for Healthcare Research and Quality. The number of pregnancy-related stroke hospitalizations grew during that period by 54%, increasing from ~4000 in 1994-1995, to ~6000 hospitalizations in 2006-2007. Between the periods of 1994-1995 and 2006-2007, the rate of any stroke — subarachnoid hemorrhage, intracerebral hemorrhage, acute ischemic stroke (AIS), transient ischemic attack, cerebral venous thrombosis (CVT), or unspecified — among antenatal hospitalizations increased by 47% (from 0.15 to 0.22 per 1000 deliveries) and among postpartum hospitalizations by 83% (from 0.12 to 0.22 per 1000 deliveries). At the end of the study period (2006-2007), the overall prevalence of pregnancy-related stroke hospitalizations was 0.71 per 1000 delivery hospitalizations. Hypertensive disorders were common in up to 28% of pregnancy-related stroke hospitalizations in 1994-1995. This increased to up to 41% in 2006-2007. In 1994-1995, up to 16% of pregnancy-related stroke hospitalizations were complicated by heart disease, not different from the up to 15% of hospitalizations in the 2006-2007 period. In 2006-2007, 32% and 53% of antenatal and postpartum hospitalizations with stroke, respectively, had concurrent hypertensive disorders or heart disease. Changes in the prevalence of these two conditions, especially hypertension, from 1994-1995 to 2006-2007, explained almost all of the increase in postpartum hospitalizations with stroke during the period between the years studied. Specific stroke subtypes were analyzed over the time period. In the antenatal group, the rate of CVT almost doubled between 1994-1995 and 2006-2007, and in the postpartum group, the rate of hemorrhagic stroke quadrupled.

A cohort study by Wasay et al studied Asian women, aged 15-45 years, with a diagnosis of first-ever symptomatic AIS (754 women) or CVT (204 women) confirmed by brain imaging. The patients with CVT had a mean age of 29 years. Pregnancy or postpartum state (49 patients; 24%) was the most common predisposing factor for CVT. On multivariate analysis, postpartum state and hemorrhagic infarct were the strongest predictors of CVT (P < 0.001). Strong predictors of AIS in young women included more traditional vascular risk factors of age over 36 years, diabetes, hypertension, dyslipidemia, recent myocardial infarction, electrocardiogram abnormalities, and blood glucose level > 150 mg/dL. While mortality was similar with CVT and AIS, neurological recovery was significantly better for patients with CVT than for those with AIS.

In a cohort study, Wang I-K et al investigated the risk of future stroke associated with hypertensive disorders in pregnancy (HDP) in 1092 pregnant Asian women (age 15-40 years) with newly diagnosed HDP from 2000-2004, as compared to 4715 randomly selected women without HDP. Both cohorts were followed until the end of 2008 to measure the incidence of future stroke of unspecified type. The HDP cohort had a higher incidence of stroke than the non-HDP cohort (30.1 vs 12.8 per 10,000 person-years), with an overall adjusted hazard ratio of 2.04 (95% confidence interval, 1.18- 3.51) for stroke. Pregnant adolescents and older women with HDP had a higher risk of future stroke than did pregnant women aged 25 to 29 years. Preterm delivery, in combination with HDP, increased the risk of future stroke by 3.22-fold.

Commentary

Women of reproductive age have an increased risk of stroke as compared to men of the same age. Oral contraceptives have been cited as contributing to this risk; however, pregnancy is an increasingly dominant cause of stroke in women in this age group. Pregnancy and the post-partum period are times of both eager anticipation and increased cerebrovascular risk. Although some of the reasons for an increase in stroke risk over the past decade are not easily explained, one reason for an increase in AIS is a well-known, traditional vascular risk factor — hypertension. The increase in the number of women who suffer a stroke during pregnancy seems to parallel the increased incidence of traditional vascular risk factors appearing in younger women. The effect of elevated blood pressure in pregnant women is particularly virulent, not only immediately during pregnancy and the post-partum period, but extending for years after delivery. Hypertensive disorders of pregnancy have been shown in multiple studies, including this recent one, to be a predictor of future stroke in women. Treatment of hypertension in pregnant women, as well as prior to pregnancy and after delivery, is crucial to decrease stroke risk throughout her lifetime.