Blood Pressure in Acute Stroke: Still No Answer for Management.

See related article, p XXX Whether intravenous or endovascular stroke therapy should be withhold in patients with acute ischemic stroke with blood pressure (BP) levels above certain thresholds is one of the major unresolved issues in acute stroke management. The post hoc analysis of data of the MR CLEAN trial (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) published in Stroke adds important new information about the risks and benefits of endovascular therapy (EVT) in acute stroke patients with different BP levels at baseline. Mulder et al analyzed BP and the effect of EVT in the MR CLEAN study and showed that the effectiveness of EVT is similar in the entire range of baseline BP of the included patients. Furthermore, BP and EVT did not interact with the occurrence of symptomatic intracerebral hemorrhage (ICH) or other safety parameters. However, there was an independent association between increasing systolic BP (SBP) levels and the risk of symptomatic ICH in the subgroup of patients with SBP>120 mm Hg, as shown previously. In addition, the authors found a similar J-shaped relationship of admission BP and functional outcome in patients who underwent EVT and their controls who received intravenous thrombolysis (IVT). The information gained from MR CLEAN provides an important message for clinicians treating patients with acute ischemic strokes with proximal vessel occlusion in the anterior circulation: BP, whatever its value is, does not influence the effectiveness of EVT. Therefore, EVT is indicated for treatment of large-vessel occlusions causing stroke irrespective of admission BP. Neither low nor high BP values advise against EVT. However, the number of patients with high (>185/110 mm Hg) and low BP in the study was small; therefore, no valid conclusions can be made on the safety of EVT in these patients. It is known for decades that BP in patients with acute stroke is elevated and that high and low BP levels are associated with poor functional outcome. Nevertheless, many relevant questions still remain unresolved. What Is the Mechanism of Elevated BP in Patients With Acute Stroke? BP is increased in ≈3 of 4 patients with acute stroke and mostly decreases spontaneously over the next few days. However, the mechanism of the transient rise in BP is unknown and the BP increase after major stroke is often claimed to be a strokespecific response (ie, post-stroke hypertension). We have shown in a population-based study that acute post-stroke BP in patients with ICH was markedly raised when compared with premorbid levels and fell rapidly thereafter. However, in patients with major ischemic strokes, acute post-event SBP was much closer to premorbid values to which these patients were presumably accustomed, with no rise in SBP before the event and only a small post-event increment. These findings suggest that the acute raise in BP mainly reflects premorbid hypertension rather than a stroke-specific response. Whether the additional small post-event increment in SBP is a direct consequence of the stroke that serves to enhance perfusion of the penumbra over collaterals is a matter of debate. Additional factors such as headache, urine retention, infection, or the psychological stress of admission to hospital could also play a role.