Blood pressure lowering in acute phase of stroke: latest evidence and clinical implications

Persistent controversy exists as to whether there are worthwhile beneficial effects of early, rapid lowering of elevated blood pressure (BP) in acute stroke. Elevated BP or 'hypertension' (i.e. systolic >140 mmHg) is common in stroke, especially in patients with pre-existing hypertension and large strokes, due to variable 'autonomic stress' and raised intracranial pressure. While positive associations between BP levels and poor outcomes are evident across a range of studies, very low BP levels and large reductions in BP have also been shown to predict death and dependence, more so for ischaemic stroke (IS) than intracerebral haemorrhage (ICH). Accumulating evidence indicates that early BP lowering can reduce haematoma expansion in ICH, but there is uncertainty over whether this translates into improved clinical outcomes, particularly since such an effect was not evident from haemostatic therapy in clinical trials. Guidelines generally recommend control of high systolic BP (>180 mmHg), but recent evidence indicates that even more modest elevation (>140 mmHg) increases risks of cerebral oedema and haemorrhagic transformation following thrombolysis in IS. Thus, any potential benefits of rapid BP lowering in acute stroke, particularly in IS, must be balanced against the potential risks of worsening cerebral ischaemia from altered autoregulation/perfusion. This paper explores current knowledge regarding the management of hypertension in acute stroke and introduces ongoing clinical trials aimed at resolving such a critical issue in the care of patients with acute stroke.