Coronary Slow Flow and No‐Reflow During Percutaneous Coronary Intervention: Contemporary Insights Into Imaging‐Guided Prediction, Prevention, and Management

ABSTRACT Coronary slow flow (SF) and no‐reflow (NR) are clinically significant complications of percutaneous coronary intervention (PCI), particularly in ST‐segment elevation myocardial infarction (STEMI) and saphenous vein graft (SVG) interventions. Angiographically defined as impaired myocardial perfusion despite restored epicardial patency, SF/NR results from microvascular dysfunction driven by distal embolization, ischemia–reperfusion injury, microvascular spasm, capillary plugging and emerging molecular mechanisms such as endothelial glycocalyx degradation and microRNA‐mediated inflammatory pathways. These processes contribute to larger infarct size, maladaptive remodeling, and increased mortality. Advanced intracoronary imaging enables lesion‐level risk stratification by identifying features such as lipid‐rich cores, thin‐cap fibroatheromas, positive remodeling, and thrombus. Image‐guided strategies, incorporating deferred stenting, selective aspiration, and tailored lesion preparation, can mitigate distal embolization. Risk stratification models (e.g., PAMI score) and recognition of sex‐ and race‐based disparities further refine procedural planning. Cost, accessibility, and emerging AI‐driven automated plaque characterization tools are important considerations for wider implementation. Preventive measures emphasize systemic optimization, adequate anticoagulation, high‐intensity statin pretreatment informed by precision dosing, dual antiplatelet therapy, and refined device techniques in thrombus‐rich or calcified lesions. Management requires early recognition, systematic exclusion of mimics such as dissection or epicardial spasm, maintenance of anticoagulation, and rapid stepwise administration of intracoronary microvasculature dilators. Device‐based delivery methods offer practical advantages but carry specific risks, including device entrapment or vessel trauma. Adjunctive therapies such as supersaturated oxygen may be considered in refractory cases. A structured, imaging‐informed algorithm integrating preventive strategies, pharmacologic escalation, and device‐assisted therapy may reduce SF/NR incidence and improve procedural and long‐term outcomes. Future research should validate imaging‐guided preventive strategies, standardized rescue protocols, and the role of AI‐driven risk assessment in diverse patient populations.