Microvascular Dysfunction in Ischemia with No Obstructive Coronary Arteries (INOCA): Pathophysiology, Diagnosis, and Emerging Therapies

INTRODUCTION: Ischemia with No Obstructive Coronary Arteries (INOCA) leads to angina and reduced blood flow in people whose main heart arteries are clear. METHODS: We reviewed articles from PubMed, Scopus, and Web of Science databases for studies published from January 2018 to December 2025 to summarize the current understanding of INOCA. We included studies on Coronary Flow Reserve (CFR), Index of Microcirculatory Resistance (IMR), and new drugs or procedures. RESULTS: CMD can be caused by problems that depend on the endothelium as well as by inflammation and oxidative stress. Diagnosis can use noninvasive tests like Cardiac Magnetic Resonance (CMR) imaging or invasive tests such as Coronary Flow Reserve (CFR) below 2.5, Index of Microcirculatory Resistance (IMR) of 25 or more, and acetylcholine provocation. Using treatments like statins, ACE inhibitors or ARBs, calcium-channel blockers, trimetazidine, and ranolazine can help manage angina and improve quality of life. DISCUSSION: INOCA is a heart condition where symptoms and risks are caused by problems in the small blood vessels, not by blockages in the main arteries. Standard angiograms may not detect these problems, which can lead to missed diagnoses. Tests such as coronary flow reserve, index of microcirculatory resistance, and acetylcholine provocation can help identify the issue and guide treatment. Recent studies show that treating the specific type of INOCA can reduce angina and improve quality of life. CONCLUSION: INOCA includes several types linked to small vessel problems and spasms, which should be identified using specific tests. Treating patients according to their INOCA type leads to better outcomes.