Effects of Intensive Blood Pressure Lowering on Perihematomal Edema in Acute Intracerebral Hemorrhage: Pooled Analysis of the Four INTERACT Trials.

OBJECTIVE: Uncertainty persists over the effect of intensive blood pressure (BP) lowering on perihematomal edema (PHE) growth in acute spontaneous intracerebral hemorrhage (ICH). We aimed to investigate the effect of intensive BP lowering on PHE growth in acute ICH. METHODS: We undertook an individual patient data pooled analysis of the 4 INTERACT trials, which all had consistent BP-lowering protocols (targeting systolic BP <140 mmHg [intensive] vs <180 mmHg [guideline] within 1 hour). PHE growth was defined as absolute volume increase and growth rate (volume increase divided by time interval [ml/h]) at 24 hours and 7 days. Linear regression models were used to evaluate the treatment effect, adjusting for covariates including baseline hematoma volume. Heterogeneity analysis was undertaken to assess the interaction with time from symptom onset to randomization and other characteristics. RESULTS: A total of 2,549 ICH patients (mean age 64 years, 35% female) with available 24-hour PHE growth data were included. Early intensive BP lowering attenuated the absolute growth at 24 hours (mean difference -1.13 mL, 95% CI -1.94 to -0.33, p = 0.006), but did not influence growth rate or the 7-day measures after adjustment. Furthermore, the treatment effect on the 24-hour PHE growth decreased with increasing time from symptom onset to randomization, with the greatest benefit observed when treatment was initiated within 2.2 h (p for interaction = 0.009). INTERPRETATION: Early intensive BP lowering significantly attenuates PHE growth at 24 hours in acute ICH, with greater benefit when initiated earlier-emphasizing the importance of early initiation of intensive BP lowering. ANN NEUROL 2026.