Abstract
Background:
The Intracerebral Hemorrhage Acutely Decreasing Arterial Pressure Trial (ICH ADAPT) demonstrated that aggressive blood pressure (BP) reduction does not affect mean perihematoma cerebral blood flow (CBF). It remains unknown if portions of the perihematoma region or watershed vascular territories (borderzones, BZs) reach ischemic thresholds after BP reduction. We tested the hypothesis that aggressive BP reduction was associated with an increased volume of critically hypoperfused tissue in ICH ADAPT patients.
Methods:
ICH patients were randomized to a target systolic BP (SBP) of <150 or <180 mmHg and imaged with CT perfusion (CTP) 2h later. A 1cm perihematoma region, and ipsilateral and contralateral internal and external BZs were outlined. The volume of tissue below CBF thresholds for ischemia (<18ml/100g/min) and infarction (<12ml/100g/min) was calculated as a percentage of the total volume of each region of interest.
Results:
ICH patients (n=73) were randomized a median (IQR) of 7.8 (13.3) h from onset and imaged with CTP 2.3 (1.0) h later. Acute hematoma volume was 17.8 (27.1) ml and mean SBP was 183±22 mmHg. At the time of CTP, SBP was lower in the <150 mmHg group (n=37, 140±18 mmHg) than the <180 mmHg group (n=36, 162±12 mmHg, P<0.001). Mean CBF in the perihematoma region did not differ between groups (<150 mmHg: 38.9±13.0 vs. <180 mmHg: 38.5±10.9 ml/100g/min, P=0.86). BP treatment did not affect the percentage of perihematoma tissue with CBF <18 (17.5±15.4 (<150 group) vs. 16.5±14.3% (<180 group), P=0.82) or <12 ml/100g/min (7.0±7.2 vs. 6.6±7.6%, P=0.93). Similar results were found in all BZs. Linear regression revealed no relationship between low SBP load (the fraction of time between randomization and CTP with SBP <150mmHg) and the percentage of perihematoma tissue with CBF <18 (β=3.62, [-6.86, 14.10]) or <12 ml/100g/min (β=1.89, [-3.30, 7.08]). There was no relationship between low SBP load and percentage of hypoperfused tissue in any BZ. Perfusion threshold analysis of time domain parameters and cerebral blood volume yielded similar results.
Conclusion:
BP reduction does not increase the volume of hypoperfused tissue, at any threshold examined, in the perihematoma region or any BZ. These data support the safety of early BP reduction in ICH.