Multivessel Assessment by Angiography-Derived Index of Microcirculatory Resistance in Patients With Nonobstructive Coronary Artery Disease

BACKGROUND: Current guidelines recommend testing for coronary microvascular dysfunction (CMD) in the left anterior descending coronary artery, and it is unclear whether multivessel assessment can improve the diagnostic yield and prognostic value of CMD. OBJECTIVES: The aim of this study was to evaluate the diagnostic and prognostic implications of multivessel CMD assessment using angiography-derived index of microcirculatory resistance (angio-IMR) in patients with nonobstructive coronary artery disease (NOCAD). METHODS: Angio-IMR was measured in all 3 major coronary arteries in 439 patients with NOCAD. Single-vessel assessment was defined as angio-IMR measurement in the left anterior descending coronary artery only. Multivessel assessment was defined as angio-IMR measurement in all 3 major coronary arteries. The primary endpoint was major adverse cardiovascular events, comprising a composite of cardiovascular death, nonfatal myocardial infarction, and hospitalization for heart failure. RESULTS: Multivessel assessment identified more patients with CMD than single-vessel assessment (46.7% vs 24.1%; P < 0.001). During a median follow-up period of 4.3 years, an increased number of vessels with CMD was associated with a higher risk for major adverse cardiovascular events after adjustment for diabetes mellitus, smoking, hypertension, hyperlipidemia, and history of myocardial infarction (adjusted HR: 1.963 per vessel; 95% CI: 1.513-2.548; P < 0.001). Multivessel assessment showed superior prognostic performance compared with single-vessel assessment when added to a clinical risk factor model (area under the curve: 0.751 vs 0.707; P = 0.034). CONCLUSIONS: Multivessel assessment by angio-IMR improved the diagnostic yield of CMD and added incremental prognostic information compared with single-vessel assessment in patients with NOCAD.