Conference Coverage

Intensive BP lowering harmful in acute ischemic stroke: ENCHANTED2/MT


 

FROM THE WORLD STROKE CONGRESS

A large randomized trial that was investigating intensive lowering of blood pressure in acute ischemic stroke patients who had undergone mechanical thrombectomy has been stopped early because of safety concerns.

“Intensive control of systolic blood pressure to lower than 120 mm Hg should be avoided to prevent compromising the functional recovery of patients who have received endovascular thrombectomy for acute ischemic stroke due to intracranial large-vessel occlusion,” the investigators conclude.

Results from the ENCHANTED2/MT trial were presented by Craig Anderson, MD, professor of neurology and epidemiology, University of New South Wales, Sydney, during the 14th World Stroke Congress (WSC) in Singapore.

The study was simultaneously published online in The Lancet.

“What our results have pretty convincingly shown is that in acute stroke patients who have undergone mechanical thrombectomy, lowering blood pressure down to a systolic of 120 mm Hg for 3 days is too low for too long. We shouldn’t go that far down,” Dr. Anderson said in an interview.

Dr. Anderson said the trial has provided an important message for clinical practice.

“This result is not what we expected, but it is a definitive result and gives us a lower safety margin for blood pressure in acute ischemic stroke patients. This, in itself, is a big step forward.”

He noted that the optimum blood pressure for these patients is not known.

“We need to do further trials to determine optimum blood pressure in these acute patients, but perhaps we should be aiming more towards 140 mm Hg,” he suggested.

“But this trial shows us that in patients who have had successful clot retrieval with endovascular treatment for acute ischemic stroke, careful blood pressure management is important to avoid levels becoming too low. We have to make sure we don’t overshoot down to 120 mm Hg or below.”

The chair of the WSC session at which the trial was presented, Jeyaraj Pandian, MD, head of neurology at Christian Medical College, Ludhiana, India, who is the current vice-president of the World Stroke Organization, said: “This is a very important result. It has major practical implications.”

As background, Dr. Anderson explained that elevated blood pressure is very common in patients who have an acute ischemic stroke, and the higher the blood pressure, the higher the chances of having a worse outcome.

“Theoretically, if we can control the blood pressure, we may be able to improve outcomes,” he said.

In 2019, the first ENCHANTED trial reported that controlling blood pressure by a moderate amount – to around 140 mm Hg, which is lower than currently recommended in the guidelines – was linked to a reduction in bleeding complications of thrombolysis and appeared safe, but it did not improve recovery, Dr. Anderson noted.

“This trial was done before mechanical thrombectomy became routinely adopted, and this procedure has now become the standard of care for large-vessel occlusion strokes, but we don’t know what we should do about blood pressure in these patients,” he added.

A smaller French trial has suggested lowering blood pressure to 130 mm Hg, rather than a more liberal 130-180 mm Hg, was safe after successful mechanical thrombectomy, but there was no effect on functional outcome.

“In stroke patients with a large-vessel occlusion, blood pressure is often elevated to very high levels. There are wide ranges of opinions on what to do about this – whether it should be lowered, and by how much,” Dr. Anderson said. “We conducted the current ENCHANTED2/MT trial to look at this issue.”

The trial randomly assigned patients who had undergone successful mechanical clot retrieval and reperfusion but whose blood pressure was still elevated to two groups. In one group, blood pressure was aggressively lowered to less than 120 mm Hg within 1 hour of reperfusion, and blood pressure was kept at this level for 3 days. In the other group, a more liberal approach was used: Blood pressure was kept at 140-180 mm Hg.

The primary endpoint was disability, as measured by the Modified Rankin Scale (mRS) score at 90 days.

The study was started in China with the intention of expanding recruitment internationally. The planned enrollment was more than 2,000 patients.

However, in March of 2022, after 821 patients had been enrolled, the data safety monitoring board (DSMB) recommended that recruitment into the trial be suspended because of a safety signal. All of the patients who had been recruited were from China.

These patients were followed to obtain the 3-month outcome results, after which the DSMB recommended that the trial be stopped because safety was still a problem.

Mean systolic blood pressure was 125 mm Hg at 1 hour and 121 mm Hg at 24 hours in the more intensive-treatment group; it was 143 mm Hg at 1 hour and 139 mm Hg at 24 hours in the less intensive-treatment group, giving an adjusted mean difference over 24 hours of 18 mm Hg.

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