Navigating coronary microvascular dysfunction: an echocardiographic triage algorithm for cardiac magnetic resonance and coronary computed tomography angiography.

The definitive diagnosis of coronary microvascular dysfunction (CMD) typically relies on invasive measurements, pointing to the pressing need for reliable noninvasive alternatives. An integrated, echocardiography-guided multimodality triage algorithm is proposed for early detection and risk stratification of suspected CMD. This framework employs frontline transthoracic echocardiography, combining global longitudinal strain (GLS) and the Doppler-derived coronary sinus flow (CSF) index, as the primary assessment tool. Patients with abnormal initial findings are selectively referred for cardiac magnetic resonance (CMR) imaging to achieve definitive tissue characterization and quantitative phase-contrast CSF validation. If CMR excludes structural cardiomyopathies but confirms significant microvascular flow impairment, the diagnostic pathway advances to coronary computed tomography angiography (CCTA) or invasive angiography to exclude obstructive epicardial disease. While standard cutoff values for the echocardiographic CSF index require further prospective validation, this multiparametric, multimodal approach bridges the gap between invasive microvascular physiology and routine noninvasive practice, providing a comprehensive strategy for early cardiovascular risk stratification.