Is blood pressure variability associated with functional outcome after EVT?

Is blood pressure variability associated with functional outcome after EVT?

It is a well-known fact that the penumbra, viable tissue surrounding the infarct core, is extremely vulnerable to CBF fluctuations, which depend on both local and systemic factors, such as cerebral vasoreactivity, collaterals and blood pressure (BP).

Prasad and colleagues explored how BP variations over time in the first days after endovascular treatment (EVT) of large vessel occlusion (LVO) impact the neurological outcome of stroke patients.

To do so, the authors conducted a multicentric observational study that included 2566 patients with LVO treated with mechanical thrombectomy, engaging 11 comprehensive stroke centers, 5 of which had prospective stroke data registries. Most of them collected data between 2012 and 2019, and one center included data from 2005.

Repeated time-stamped systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) within the time frame of 72 hours post-EVT were gathered from the participating centers, with the goal of addressing BP variability after thrombectomy. The primary outcome was stroke-related disability measured using the modified Rankin Scale (mRS) at 90 days.

Blood pressure variability for SBP, DBP, and MAP was sorted into clusters/trajectories using group-based trajectory modeling and tertile classification. In a second step, the authors used multivariate logistic regression modeling in order to adjust for possible confounders such as patient age, sex, baseline NIHSS, preprocedural ASPECTS, admission MAP, time from last known well to reperfusion, postprocedural TICI score, and the overall number of per patient BP measurements.

In the main analysis, which included a total of 102,030 time-stamped BP measurements and a mean number of 50 recorded BP measurements per patient, almost two thirds of patients were classified as having moderate BP variability. BP variability tended to be higher in first hours after thrombectomy. Most importantly, the results suggest that stroke patients with high BP variability after EVT are at greater risk of an unfavorable functional outcome. The explanation might be in the loss of the brain’s ability to sustain blood flow autoregulation mechanisms after stroke, exposing the penumbra area to deleterious fluctuations in systemic blood pressure.

Moreover, this study reinforces the existing evidence of an association between high systolic BP and unfavorable functional outcome in stroke patients. Interestingly, there was no significant association between BP variability and hemorrhagic transformation or symptomatic intracranial hemorrhage (sICH), which is in accordance with previous investigations, such as the BEST study.

Although this study does not provide a definitive answer on whether increased BP variability after thrombectomy is a marker of disease severity or a contributor to the development of poor outcomes, it has important strengths, including the large cohort size and multicenter design, with assessment of multiple BP parameters and adjustment for various confounders. The use of some retrospective data and lack of information on the anesthetic management and the class, dosage and timing of antihypertensive drugs administered during the procedure and in the aftercare are, nonetheless, relevant limitations.

In conclusion, the results of this study contribute to the understanding of BP variability and functional outcome of patients treated with EVT for acute ischemic stroke due to LVO. Further investigation is needed to identify the ideal candidates for possible interventions directed at reducing BP variability, as well as the timing of intervention.

Hopefully, studies such as BEST-II (NCT04116112), OPTIMAL_BP (NCT04205305), ENCHANTED 2 (NCT04140110) and CRISIS I will bring us closer to a solid conclusion.