The authors of this study note that reduction in blood pressure (BP) is the most effective intervention to prevent stroke. Lacunar strokes (small subcortical brain infarcts) comprise around 25% of ischaemic strokes and are mainly due to disease of the small penetrating arteries. Despite their frequency, it is not known if there are optimum BP targets to prevent recurrent stroke in such patients.
Two target ranges of systolic BP were assessed as part of the Secondary Prevention of Small Subcortical Strokes (SPS3) trial and the results of this analysis are presented in this article. A total of 3,200 adults (aged ≥30 years) with a recent (within 180 days) MRI-confirmed non-disabling lacunar stroke were randomised to a systolic BP target of 130-149 mmHg (n=1,519) or <130 mmHg (n=1,501). After 1 year, mean systolic BP was 138 mmHg (95% CI 137–139) and 127 mmHg (95% CI 126–128), respectively.
The mean duration of follow-up was 3.7 years. The primary endpoint was all stroke (intention to treat) – the annualised stroke rate was 2.25% in the lower target group and 2.77% in the higher target group (hazard ratio [HR] 0.81, 95% CI 0.64-1.03, p=0.08). The lower target group was associated with a lower rate of intracerebral haemorrhage (0.11% vs. 0.29% per year; HR 0.37, 95% CI 0.15-0.95, p=0.03). Mortality and the rate of serious treatment-related adverse events did not differ significantly between groups.
The author of a related editorial notes that the magnitude of reduction in recurrent stroke was less than that seen in previous trials of BP-lowering, and they suggest possible explanations for this. If these data are viewed alongside other evidence for BP lowering in patients with previous stroke, then they say that the 19% reduction in rate for all stroke is likely to be a real rather than a chance observation, and they suggest that the trial may have been underpowered, as the rate of recurrent stroke was around half of what was anticipated. Consequently, the study may also have been underpowered to identify or exclude confidently a clinically important increase in serious complications of hypotension with systolic BP lower than 130 mmHg.
Based on these findings, the editorial author recommends that clinicians endeavour to achieve and maintain systolic blood pressures <130 mmHg in patients who have survived ≥2 weeks after subcortical lacunar ischaemic stroke. BP should however be lowered gradually, in view of complications related to hypotension. The safety and effectiveness of this target BP needs to be evaluated in survivors of other types of stroke.