Recent Recent England Journal of Medicine The study assessed whether early control of blood pressure in ambulances results in favorable clinical outcomes in patients with undifferentiated acute stroke.

Test: Intensive emergency blood pressure reduction for hyperacute stroke. Photo source: Jaromir Chalabala / Shutterstock.com

Stroke treatment

Intensive treatment to lower blood pressure is commonly clinically useful in patients with acute intracerebral hemorrhage. Nonetheless, studies examining blood pressure lowering alone have produced inconsistent results, which could also be as a result of differences in study designs, populations, or interventions. Clinical outcomes could also be improved if blood pressure-lowering interventions are initiated as early as possible; nevertheless, this may increasingly be complicated in patients with acute ischemic stroke.

The previous two studies showed similar results regarding the effectiveness and safety of prehospital blood pressure-lowering interventions inside hours of acute stroke. In patients with intracerebral hemorrhage, poorer outcomes were noted in those that received the glyceryl trinitrate patch in comparison with those that received the sham patch.

About this study

The present study reports the outcomes of the INTERACT (Intensive Ambulance Delivered Blood Pressure Reduction in Hyper-Acute Stroke Trial) 4 trial. The aim of INTERACT 4 was to guage the effectiveness and safety of initiating intravenous antihypertensive treatment by ambulance inside two hours of an acute stroke.

The initial group consisted of patients treated by ambulance inside two hours of the onset of symptoms, suspected of getting an acute stroke causing motor deficit and whose systolic blood pressure was not less than 150 mm Hg. Study participants were randomly assigned to receive standard blood pressure treatment or immediate intervention to lower systolic blood pressure to a goal range of 130–140 mm Hg.

The first safety consequence was the occurrence of any serious antagonistic event. The first efficacy consequence was assessed using the Modified Rankin Scale, where a rating of zero meant no symptoms and a rating of six meant death. Outcomes were recorded 90 days after randomization.

Findings

The sample included 2,404 patients in China with a mean age of 70 years. The intervention group consisted of 1,205 participants, and the median time interval between symptom onset and randomization was 61 minutes.

Mean blood pressure at randomization was 178/98 mm Hg. To verify stroke, imaging tests were performed in 2,204 patients, of which hemorrhagic stroke was confirmed in 46.5% of patients.

After patients arrived on the hospital, the mean systolic blood pressure values ​​within the intervention and usual groups were 158 and 170 mm Hg, respectively. No differences in functional outcomes were observed between the intervention and usual care groups. Furthermore, the incidence of great antagonistic events was similar in each study groups.

Amongst patients with hemorrhagic stroke, prehospital blood pressure reduction was related to a decreased likelihood of poor functional consequence. This association was reversed amongst patients with cerebral ischemia, who were at increased risk of poor functional consequence.

Strengths and limitations

The foremost strength of IMPACT 4 is the supply of treatment by physicians in emergency services. Additional strengths include an easy consent process, the power to lower blood pressure with an easy intravenous treatment regimen, and a high rate of protocol compliance.

One limitation was the involvement of physicians in emergency services, which limits the generalizability of the outcomes. Moreover, the present study was conducted in China, where the character of stroke is different from that in North America and Europe.

For instance, in North America the speed of ischemic stroke is higher, while in Europe the incidence of intracerebral hemorrhage is high. Furthermore, intravenous urapidil will not be widely available outside China.

On account of lack of generalizability, the research approach could also be less appropriate for paramedic-led emergency services and when strokes are brought on by a minor neurological deficit. Data quality can also have been reduced as a result of several aspects, corresponding to quarantine restrictions throughout the coronavirus disease 2019 (COVID-19) pandemic, open-label design, variability in other medical care, and broad inclusion criteria.

Conclusions

This study showed that rapid initiation of treatment inside two hours of intensive blood pressure lowering in patients with acute stroke didn’t end in significant improvement in functional outcomes compared with standard of care, during which blood pressure control begins upon arrival on the hospital. In patients with cerebral ischemia and hemorrhagic stroke, the intervention can have had different effects.