Abstract WMP103: Comparative Impact of Extent of Lobar Intracerebral Hemorrhage Removal on Outcome in the MISTIE III and STICH II Trials

Introduction: The Minimally Invasive Surgery Plus Recombinant Tissue Plasminogen Activator for Intracerebral Hemorrhage Evacuation Phase III trial (MISTIE III) concluded that the extent of hematoma reduction confers a mortality and functional benefit. It is unclear if a minimum extent of evacuation is needed for mortality and functional outcome benefit in lobar cases with MISTIE and with open surgical interventions. Objective: We analyzed the effect of extent of lobar ICH evacuation on clinical outcome at 180 days after undergoing the MISTIE procedure and open craniotomy, in the context of the MISTIE III and STICH II clinical trials, respectively. Methods: Patients randomized to the surgical arm with lobar ICH, who underwent the procedure in the MISTIE III trial (n=84) and the STICH II trial (n=266) were analyzed, excluding cases crossing over to surgery. We assessed end of treatment ICH volume on post procedure CT scans and % hematoma evacuation, in relation to survival and likelihood of mRS 0-3. Cubic spline modeling with dichotomized outcome was used to compare the extent of hematoma evacuation on clinical outcome. Results: End of treatment volume of < 28 mL in lobar ICH MISTIE III patients and < 30 mL in STICH II trial patients showed a significantly increased probability of achieving an mRS of 0-3 at 180 days (p<0.03, p<0.006, respectively). This threshold was achieved in 83.1% of lobar cases undergoing MISTIE and in 92.1% of surgical cases in STICH II. Achieving survival benefit at 180 days trended towards improved probability with further hematoma volume reduction without a threshold value in MISTIE III, and was significant per mL reduction in STICH II (p<0.001). Analysis by percent of hematoma evacuation trended toward better probabilities of survival and improved functional outcome but were not significant. Conclusion: This analysis confirms that extent of hematoma evacuation is important in attaining the benefits of both minimally invasive and open surgical interventions in non-herniating lobar ICH patients randomized in clinical trials. Extent of ICH evacuation must be considered in the analysis of comparative effectiveness of various techniques and in the design of future trials.