Prehospital Blood Pressure Reduction Harmful in Ischemic Stroke

Intensive blood pressure (BP) control administered in the ambulance prior to arrival in the hospital had no overall effect on functional outcomes in patients with undifferentiated acute stroke, according to study results published in the New England Journal of Medicine (NEJM).

Researchers conducted an open-label, randomized trial (INTERACT4; ClinicalTrials.gov Identifier: NCT03790800) at 51 hospitals in China between March 2020 and August 2023 to assess the safety and efficacy of initiating intravenous antihypertensive treatment in the ambulance within 2 hours after an acute stroke.

Adults with a presumed acute stroke, defined by a Field Assessment Stroke Triage (FAST) score of 2 or greater that included an arm motor deficit; elevated systolic BP (≥150 mm Hg); and the ability to commence treatment within 2 hours after symptom onset or after they were last known to be well were eligible for inclusion. Patients were randomly assigned 1:1 to receive prehospital BP reduction or usual BP management. Neurologic impairment was assessed according to the National Institutes of Health Stroke Scale (NIHSS), which ranged from 0 to 42, with higher scores indicating greater neurologic deficits.

The primary efficacy outcome was functional status at 90 days and the primary safety outcome was any serious adverse event (AE). Ordinal logistic regression was used in statistical analyses.

A total of 2404 patients (mean age, 70; men, 61.7%; mean systolic BP at randomization, 178 mmHg; median time from symptom onset to randomization, 61 minutes) were included in the intention to treat population, 1205 of whom were assigned to the intervention group and 1199 of whom were assigned to the usual-care group.

Of the 2240 patients who received a diagnosis of stroke confirmed by imaging, 1041 (46.5%) had hemorrhagic stroke, 522 of whom were assigned to the intervention group and 519 of whom were assigned to the usual-care group.

The mean systolic BP in the intervention and usual-care groups at the time of arrival at the hospital was 159 mmHG and 170 mmHG, respectively. At 7 days, the mean systolic BP in the intervention and usual-care groups was 136 mmHg and 138 mmHg, respectively.

Overall, no significant between-group differences were observed regarding the distribution of scores on the modified Rankin scale (mRS) at 90 days (common odds ratio [OR], 1.00; 95% CI, 0.87-1.15).

Differences in the effect of prehospital BP reduction according to stroke type, however, were observed. Starting intensive antihypertensive therapy before reaching the hospital was associated with a decreased likelihood of a poor functional outcome at 90 days in patients with hemorrhagic stroke (common OR, 0.75; 95% CI, 0.60-0.92), but an increased likelihood of the same in patients with cerebral ischemia (common OR, 1.30; 95% CI, 1.06-1.60).

The incidence of serious AEs did not significantly differ between the intervention and usual-care groups (27.5% vs 28.7%, respectively).

Study limitations included the reduced generalizability of results and open-label design, as well as the use of broad inclusion criteria and risk-based monitoring during quarantine restrictions in the COVID-19 pandemic.

“In patients with acute stroke and elevated blood pressure, the rapid initiation of intensive blood pressure reduction to reach a target systolic blood pressure of 130 to 140 mm Hg in the ambulance within 2 hours after symptom onset had no benefit with regard to functional outcome in patients with undifferentiated stroke as compared with the standard approach of initiating blood pressure management after arrival at the hospital,” the researchers concluded.

Disclosures: This research was supported by Takeda Pharmaceuticals Chine. Please see the original reference for a full list of disclosures.