What Is Optimum BP in Stroke Thrombectomy?

June 25, 2018

GOTHENBURG, Sweden — Both low and high baseline systolic blood pressures are associated with an increased risk for poor outcome in patients with acute ischemic stroke undergoing endovascular therapy, new results from a large registry study suggest. 

Researchers found the optimum systolic pressure to be 135 mm Hg; increasing values above this level were associated with increased risk for symptomatic intracranial hemorrhage and a lower chance of successful reperfusion.

The study was presented here by Sophie van den Berg, Academic Medical Center, Amsterdam, the Netherlands, at the recent 4th European Stroke Organisation Conference (ESOC) 2018.

"Our results suggest that the treatment of high blood pressure may be beneficial in patients undergoing endovascular therapy and should be investigated in randomized controlled trials," she concluded.

Commenting on the study for Medscape Medical News, Alistair Webb, MD, University of Oxford, United Kingdom, also called for more trials.

"This study tells us high blood pressure is a negative prognostic marker in the situation of thrombectomy, but it doesn't tell us more than that," he said. "Patients to be given thrombolysis would have their blood pressure lowered anyway if they were very hypertensive. We need randomized trials to give us more information on this in thrombectomy, and these are now underway."

van den Berg noted that high systolic blood pressure in the acute phase of ischemic stroke is associated with an increased risk for symptomatic intracranial hemorrhage and poor outcome, but the extent to which systolic blood pressure affects outcome after endovascular treatment in clinical practice is not well known.

"Clinicians are wondering whether they should lower blood pressure in hypertensive patients who are eligible for endovascular therapy," van den Berg said.

The current study assessed the relation between systolic blood pressure before endovascular therapy and reperfusion, symptomatic intracranial hemorrhage, and 90-day functional outcome (modified Rankin Scale [mRS] score) in the MR CLEAN Registry.

The MR CLEAN registry is an observational, prospective, multicenter study of endovascular therapy in routine clinical practice in the Netherlands.

The study included 1488 patients who underwent endovascular therapy for stroke between 2014 and 2016. The average systolic blood pressure prior to the procedure was 150 mmHg, and 7% of patients had systolic pressure above 185 mm Hg. Half the patients had a history of hypertension. 

After adjustment for prestroke mRS score, sex age, baseline National Institutes of Health Stroke Scale score, collateral grade, previous hypertension and general anesthesia, results showed the relation between systolic blood pressure and poor functional outcome took the form of a nonlinear U-shaped curve, with the lowest chance of a poor outcome (mRS score, 3 - 6) at a systolic pressure of 135 mm Hg.

For systolic pressures above 135 mm Hg, the risk for a poor outcome increased by 13% for each 10–mm Hg increase (hazard ratio [HR], 1.13; 95% confidence interval [CI], 1.07 - 1.19).  

For systolic pressures below 135 mm Hg, the risk for a poor outcome increased by 6% for each 10–mm Hg decrease, although this correlation was not statistically significant (HR, 1.06; 95% CI, 0.92 - 1.21).  

The relationship between systolic pressure and mortality also showed a nonlinear U-shaped curve, with the lowest mortality seen at the 135–mm Hg mark.

The risk for symptomatic intracranial hemorrhage (which occurred in 6% of patients) showed a more linear relationship with increasing systolic blood pressure, with risk increasing by an average of 13% for each 10–mm Hg increase (HR, 1.13; 95% CI, 1.04 - 1.24).

The probability of successful reperfusion showed a linear relationship with systolic blood pressure; the chances of reperfusion were reduced with increasing pressures. van den Berg suggested this might be caused by the increased hydraulic forces associated with higher pressures making the mechanical removal of the clot more difficult.

Patients with systolic blood pressure above 185 mm Hg had much higher risks for a bad outcome ,with 78% having an mRS score of 3 to 6 compared with 61% of those with pressures below 185 mm Hg (HR, 1.63; 95% CI, 1.10 - 2.42).

Whether lowering blood pressure in stroke patients with hypertension undergoing endovascular therapy is beneficial is now being investigated in two randomized trials: RIGHT-2 and MR ASAP.

4th European Stroke Organisation Conference (ESOC) 2018. Large Clinical Trials 2. Presented May 18, 2018.

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