, new research suggests.
In a randomized trial of 220 women with preeclampsia or gestational hypertension, those who took daily postpartum BP readings and received clinician-guided advice for titrating antihypertensives had a 5 mm Hg–lower average diastolic BP at 9 months, compared with those receiving usual care.
Jamie Kitt, DPhil, from the University of Oxford (England) presented these findings from the Physicians Optimized Postpartum Hypertension Treatment (POP-HT, NCT04273854) clinical trial at the American Heart Association scientific sessions. The study was simultaneously published online in JAMA, and a cardiac imaging substudy was published online in Circulation.
“This trial identifies a potential need for a paradigm shift in the way women affected by hypertensive pregnancy are managed postnatally,” Dr. Kitt said. “If a 5–mm Hg improvement in BP is maintained longer term, it can result in about a 20% reduction in lifetime cardiovascular risk.”
The imaging substudy suggests that short-term postnatal optimization of BP control following hypertensive pregnancy through self-monitoring and physician-guided antihypertensive titration is linked with better cardiac remodeling changes seen by cardiovascular magnetic resonance and echocardiography.
POP-HT “proves for the first time that the first few weeks after delivery are a critical time that can determine the long-term cardiovascular health of the mother,” senior author Paul Leeson, PhD, also from the University of Oxford, who presented the findings in a press briefing, said in an interview.
“Interventions during this period can have long-term beneficial impacts on cardiovascular health,” he said. “These findings rewrite the textbook on our understanding of how and why hypertensive pregnancies associate with later cardiovascular disease in the mother.”
Next, Dr. Leeson said, “We need to work out the best ways to implement these interventions “at scale. Then we can ensure all women who have hypertensive pregnancies can get access to the long-term cardiovascular benefits we have demonstrated are possible through improving postpartum cardiac care,” he said, adding that “this is entirely achievable using current available technologies.”
Hypertension in pregnancy
About 1 in 10 pregnant women develop hypertension in pregnancy (preeclampsia or gestational hypertension), and 1 in 3 such women go on to develop chronic hypertension within 10 years, “when they are usually still in their 30s or 40s,” Dr. Leeson said.
During pregnancy, the heart remodels to cope with pregnancy, and it undergoes more severe changes if BP is high. Then during the 6 weeks after giving birth, this remodeling rapidly reverses.
Higher blood pressure in young adulthood is associated with a twofold higher risk of subsequent myocardial infarction and stroke. And abnormal cardiac remodeling postpartum is also linked with higher cardiovascular risk.
Self-monitoring blood pressure during the postpartum period may be a “critical window” for intervention.
Previously, the research group performed a pilot study, the Self-Management of Postnatal Antihypertensive Treatment (SNAP-HT) trial and the SNAP-extension trial, which compared a BP self-monitoring intervention with usual care in 91 women with gestational hypertension or preeclampsia requiring postnatal antihypertensive treatment.
Diastolic BP, which drives cardiovascular risk in younger populations, was 4.5–mm Hg lower at 6 months postpartum and 7–mm Hg lower at 4 years post partum in patients randomly assigned to BP self-management vs. usual care – even after they were no longer taking antihypertensives.
Building on these findings, the POP-HT trial enrolled 220 pregnant women seen at Oxford University Hospitals in the United Kingdom who were age 18 years or older, had either gestational hypertension or preeclampsia, and still required antihypertensives when they were being discharged from hospital after giving birth.
Following a baseline visit at day 1-6 after delivery, while in the postnatal ward, the patients were randomly assigned 1:1 to the intervention group (112 women) or usual-care group (108 women).
They had an average age of 32.6 years; 40% had gestational hypertension, and 60% had preeclampsia.
Women in the usual-care group typically received a BP review at 7-10 days after hospital discharge with a community midwife, and another at 6-8 weeks with their general practitioner.
The women in the intervention group were given and taught to use a Bluetooth-enabled OMRON Evolv BP monitor (Omron Healthcare Europe) while on the postnatal ward, and they installed a smartphone app on their mobile phones that transmitted self-monitored BP readings to a National Health Service-hosted, web-based platform.
They were instructed to take daily BP measurements (twice daily if out of target range). Dose titration of antihypertensives after hospital discharge was guided remotely by research clinicians, according to a guideline-based algorithm.
Patients in both groups had four study visits when their BP was measured: visit 1 (baseline) between days 1 and 6 post partum; visit 2 at week 1; visit 3 at week 6; and visit 4 between months 6 and 9 post partum.
Similar antihypertensive classes were prescribed in each group (enalapril 57%, nifedipine 27%, and labetalol 30% for intervention vs. enalapril 43%, nifedipine 30%, and labetalol 27% for control).
At 6 weeks, approximately 30% of participants in each group were still taking medication; this dropped to approximately 12% by visit 4.
The primary outcome – the mean 24-hour diastolic BP at visit 4 (roughly 9 months post partum), adjusted for baseline postnatal diastolic blood pressure – was 5.8–mm Hg lower in the intervention group than in the control group (71.2 mm Hg vs. 76.6 mm Hg; P < .001).
Secondary outcomes – between-group differences in systolic BP at 9 months, BP-related postnatal admission, and cardiac remodeling assessed by cardiac magnetic resonance – were all better in the intervention group.
The mean 24-hour average systolic BP at 9 months post partum, adjusted for baseline postnatal systolic BP was 6.5–mm Hg lower in the intervention group than in the control group (114.0 mm Hg vs. 120.3 mm Hg; P < .001).
There was an absolute risk reduction of 20% and a relative risk reduction of 73.5% in postnatal readmission. The number needed to treat to avoid one postnatal readmission was five, which “has potential for big cost savings,” said Dr. Leeson.
Blood pressure post partum can be improved with self-monitoring and physician-guided medication adjustment, Dr. Leeson summarized. The blood pressure remains low for at least 9 months, even when medication is stopped, and the intervention leads to beneficial cardiac remodeling.