High Systolic BP After EVT for Stroke Tied to Poor Outcomes

Erik Greb

November 26, 2020

Higher maximum systolic blood pressures during the first 6 hours after endovascular treatment (EVT) are associated with worse functional outcomes in patients with acute ischemic stroke, a new study suggests.

High blood pressure during this period was also associated with increased risk of symptomatic intracranial hemorrhage (sICH) and a more severe early neurologic deficit.

These findings were presented at the European Stroke Organization-World Stroke Organization (ESO-WSO) Conference 2020.

Patients who present with ischemic stroke often have elevated blood pressure. Although blood pressure facilitates cerebral perfusion and improved outcomes, excessive blood pressure could cause hemorrhage. Little data are available about the relationship between blood pressure in the first hours after EVT and subsequent patient outcomes.

Noor Samuels, MD, of the Departments of Radiology & Neurology of the Erasmus MC University Medical Center in Rotterdam, the Netherlands, and colleagues sought to investigate this relationship and to assess whether the associations between blood pressure and outcomes were influenced by reperfusion grade.

The investigators analyzed data from the MR CLEAN registry, which included all patients who underwent EVT for ischemic stroke in the Netherlands. They included patients treated between March 2014 and November 2017 in their analysis. To reduce the risk of confounding by indication, Samuels and colleagues focused on eight centers that systematically recorded blood pressure values after EVT. They evaluated patients' mean, maximum, and minimum systolic blood pressure during the first 6 hours after EVT.

The study's primary outcome was the modified Rankin Scale score at 90 days. Samuels and colleagues also examined early neurologic deficit, which they defined as NIH Stroke Scale score at 24 to 48 hours, and sICH later than 6 hours after EVT as secondary outcomes.

Researchers performed a multivariable regression analysis, adjusted for center and potential confounders, to evaluate the association between systolic blood pressure with each outcome. The potential confounders they considered were age, collateral score, medical history, and baseline stroke severity. They also tested for interactions between systolic blood pressure parameters and recanalization status.

They evaluated whether the association between blood pressure and outcome was modified by reperfusion grade, which they defined using the extended thrombolysis in cerebral infarction score.

Linear Association

Samuels and colleagues identified 1796 patients in the registry and included 1161 in their analysis. They excluded patients who were younger than 18 years, those with stroke in the posterior circulation, and those for whom no blood pressure data were available.

The investigators observed that patients with blood pressure greater than 150 mmHg were more likely to be older, have hypertension, and have diabetes, compared with other patients. Patients with high blood pressure were less likely to have a good collateral score compared with other patients.

In the adjusted analyses, higher maximum systolic blood pressure was associated with worse functional outcome at 90 days. The adjusted common odds ratio (acOR) for worse outcome was 0.93 per 10-mmHg increase in blood pressure (95% CI, 0.88 - 0.98). Higher maximum systolic blood pressure also was associated with higher risk of sICH (acOR, 1.17 per 10-mmHg increase; 95% CI, 1.02 - 1.36) and more severe early neurologic deficit (adjusted beta, 0.31 per 10-mmHg increase; 95% CI, 0.14 - 0.49).

Minimum systolic blood pressure had a nonlinear association with functional outcome. Minimum systolic blood pressure below 124 mmHg was associated with worse outcomes (acOR, 0.85 per 10-mmHg decrement; 95% CI, 0.76 - 0.95). Minimum systolic blood pressure above that level also was associated with worse outcomes (acOR, 0.81 per 10-mmHg increment; 95% CI, 0.71 - 0.92).

They found no association between minimum systolic blood pressure and sICH, however. Minimum systolic blood pressure higher than 124 mmHg was associated with larger neurologic deficits (acOR, 0.76 per 10-mmHg increment; 95% CI, 0.23 - 1.28).

Reperfusion rates did not affect the association between systolic blood pressure and functional outcome.

Unanswered Questions

Dr Ralph L. Sacco

The study methodology is strong, Ralph L. Sacco, MD, professor and Olemberg chair of neurology at the University of Miami, Florida, told Medscape Medical News. "It's an important clinical question," he said.

The first 6 hours are "a critical period in the post-EVT patient." During this time, the blood vessel that has been opened could close. If it was not fully opened, then maintaining blood pressures to perfuse parts of the brain is critical in the early phases after EVT, Sacco said. "If the artery's completely open by EVT, which is always the best-case scenario, there still is the concern that it could close again or there could be some brain tissue injury that is still occurring after the acute stroke."

Neurologists at stroke centers must pay more attention to managing patients' blood pressure after EVT, said Sacco. These new results "would argue that we shouldn't let it go too high because of the risk of hemorrhage."

At the same time, lowering the blood pressure excessively would reduce blood flow to the brain that "has just been starved for blood and oxygen," said Sacco. "Studies like this are often precursors to the next study, which is a randomized trial. It's an important question that we still don't have the complete answer for."

The MR CLEAN registry was sponsored by Stichting Toegepast Wetenschappelijk Instituut voor Neuromodulatie. Samuels and Sacco have reported no relevant financial relationships.

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