2084 The Relationship Between Intraoperative Donor and Recipient Flow Rates With Post-operative Angiographic Outcomes in Direct Revascularization for Moyamoya Disease

INTRODUCTION: The correlation between intraoperative flow measurements and post-operative angiographic revascularization for moyamoya disease is not well characterized. METHODS: Consecutive patients undergoing direct bypass for moyamoya disease were studied. Donor and recipient flows were measured intraoperatively. The primary outcome measure was proportion of MCA territory supplied by the donor graft at 6 months, A (MCA). RESULTS: One hundred and two bypasses in 84 patients (median age 42.6 yo, 75.5% female) were included. Graft patency at 6 months was 97.1%, with 87.3% of grafts demonstrating hypertrophy. Matsushima grading at 6 months were 48.0% (A), 22.5% (B), and 28.4% (C). Preanastomosis STA cut flow had no statistical correlation to postanastomosis M4 flow. Postanastomosis STA flow (mean and max) demonstrated moderate correlation to postanastomosis proximal (−0.609 < r < −0.642) and distal (0.550 < r < 0.564) M4 flow (all p<0.001). Mean and maximum postanastomosis STA flows were significantly higher in the Matsushima A (18.3 and 25.5 mL/min respectively) compared to Matsushima B + C (10.4 and 14.2 mL/min respectively, p<0.01). Using logistic regression and controlling for various factors, STA hypertrophy (p=0.029) and postanastomosis mean STA flow (p=0.017) were independent predictors of Matsushima A. Hemispheres with postanastomosis mean proximal M4 flows = −10 mL/min had a greater proportion of MCA territory supplied by the bypass graft (median 70%, Z=−2.29, p=0.022), but this relationship was not observed for distal M4 flows. For hemispheres with M4 flows <±10 mL/min, donor grafts provide a median of 50% A (MCA). All hemispheres achieved 100% A (MCA) coverage through the combination of the graft and native collaterals. CONCLUSIONS: Intraoperative donor and recipient flow rates have positive relationships to A (MCA) at 6 months. However, all patients achieved appropriate angiographic coverage irrespective of intraoperative flow rates. Further studies are required to refine clinically meaningful intraoperative predictive tools.