Up until now, most current stroke guidelines have recommended against lowering of blood pressure in hypertensive patients with suspected stroke, mostly based on pathophysiological considerations and low-quality evidence. New evidence emerges from the INTERACT 4 study. This study included 2404 patients in the prehospital setting in China who had a suspected stroke within two hours of symptom onset and were hypertensive. Patients were randomized to antihypertensive treatment within the ambulance with a target blood pressure of 130-140 mmHg (using intravenous boli of the α₁-adrenoceptor antagonist urapidil) or usual care.
While there was no difference in the primary outcome (functional neurological outcome) between both treatment groups, there were significant differences in the subgroups of patients with ischemic stroke and intracerebral haemorrhage. Patients with ischemic stroke showed harm caused by prehospital antihypertensive treatment (common odds ratio for worse functional outcome: 1.30), but patients with intracerebral haemorrhage had improved outcomes (common odds ratio for worse functional outcome: 0.75). It is important to note that the rate of ICH in this study was 43% - higher than to be expected in a comparable European population.
Several conclusions can be drawn from this important trial:
1) There is no benefit in antihypertensive treatment in undifferentiated prehospital patients with suspected stroke in the prehospital setting and evidence of harm in the subgroup of ischemic stroke – therefore it should be avoided in this setting in general.
2) The large positive treatment effect in the subgroup of patients with intracerebral haemorrhage points towards a high need of fast identification and antihypertensive treatment in those patients, in line with previous randomized trials.
3) These findings imply that accurate prehospital differentiation of ischemic stroke and intracerebral haemorrhage using imaging (mobile stroke units) or biomarker tests would have immediate therapeutic implications.
Key Points:
- Prehospital antihypertensive treatment of patients with suspected stroke did not lead to a positive effect in a large randomized trial
- Patients later diagnosed with ischemic stroke showed harm, but patients diagnosed with intracerebral haemorrhage benefited from prehospital antihypertensive treatment
- This indicates the need for early differentiation of patients with suspected stroke
References:
Li G, Lin Y, Yang J, et al. Intensive Ambulance-Delivered Blood-Pressure Reduction in Hyperacute Stroke. N Engl J Med. Published online May 16, 2024. doi:10.1056/NEJMoa2314741
Publish on behalf of the Scientific Panel on Stroke