The landmark 2016 ATACH II trial compared aggressive blood pressure lowering (110-139 mmHg) with standard BP-targets (140-180) in patients with spontaneous ICH, and found no difference between the groups. The main endpoints were mortality and functional neurological outcome (modified Rankin scale). The only discernible difference was a tendency towards less haematoma expansion in the intervention (lower BP-target) group, but this failed to reach statistical significance.
The same authors have now published a post-hoc analysis of data from the patient subgroup with deep haemorrhage (basal ganglia and thalamus), which constituted no less than 87% of the entire study population. Interestingly, they were able to show a significantly lower risk of haematoma expansion in the intervention group (OR 0,61). However, this had no impact on functional outcome as the distribution of modified Rankin scores was similar in both study arms. Basal ganglia bleeds seem to account for most of the observed effect, whereas the thalamic haematomas do not appear to be significantly affected by specific BP-targets. This may lead one to speculate if there are important differences between brain regions that determine the nature of bleeding, risk of expansion and susceptibility to changes in BP. The article expounds on this subject and the authors argue convincingly that the pathophysiology is indeed variable between different bleeding sites.
These speculations notwithstanding, these results are unlikely to change practice. As we already knew from the original publication, it seems reasonably safe to lower BP to below 140 (slightly increased risk of renal adverse events) but it doesn’t seem to offer any benefit. Personally, I have adapted a pragmatic stance, actively lowering BPs >180 mmHg, whilst keeping a watchful eye on any BP >160 mmHg. I would love to hear your take on these results and on your practice. Feel free to comment.