Abstract 4369137: Elevated Coronary Angiography-Derived Index of Microvascular Resistance Predicts Poor Prognosis in Angina with Non-Obstructive Coronary Artery Disease

Background: Angina with non-obstructive coronary artery disease (ANOCA) prognosis requires improved prediction tools. The prognostic role of coronary angiography-derived index of microvascular resistance (caIMR) remains underexplored. Research Question: Does elevated caIMR correlate with worse clinical outcomes in ANOCA patients and improve prognostic prediction? Methods: ANOCA patients were selected from a prospective coronary artery disease registry (NCT05337319). Computational fluid dynamics analyzed angiography images to quantify caIMR. Patients were stratified by caIMR >25 (microvascular dysfunction) or ≤25 (non-dysfunction). Inverse probability of treatment weighting adjusted baseline differences. The primary endpoint was the 18-month patient-oriented composite outcome (POCO): cardiovascular death, heart failure hospitalization, or rehospitalization for ischemic symptoms. Results: Among 917 ANOCA patients, 608 (66.3%) had microvascular dysfunction. Fifty-five POCO events occurred over median 483-day follow-up. After adjustment, the high caIMR group had significantly higher POCO risk (adjusted hazard ratio [HR] 2.78, 95% confidence interval [CI] 1.20-6.46) and higher rehospitalization risk (adjusted HR 2.98, 95% CI 1.06-8.38) versus low caIMR. Continuous caIMR independently predicted POCO risk (adjusted HR 1.03 per unit, 95% CI 1.01-1.05, p=0.002). Adding caIMR to clinical models improved prediction: net reclassification improvement 0.027 (95% CI 0.004-0.051, p=0.025); integrated discrimination improvement 0.317 (95% CI 0.054-0.580, p=0.018). Conclusions: Elevated caIMR independently predicts increased POCO risk in ANOCA patients, showing a dose-response relationship. Incorporating caIMR enhances traditional prognostic models, providing objective quantitative data for risk stratification and treatment decisions.