Long IVUS-Attenuated Plaque Without No-Reflow: Histological Findings of Captured Embolic Debris and Implications for the Interpretation of IVUS Attenuation: A Case Report

Background The no-reflow phenomenon during percutaneous coronary intervention (PCI) is commonly associated with distal embolization from high-risk coronary plaques, including lesions with intravascular ultrasound (IVUS)-defined attenuation. Histopathological analysis of embolic debris captured during PCI is rarely reported and may provide additional insights into the relationship between plaque characteristics and coronary flow outcomes. Case Summary An 84-year-old man presented with acute coronary syndrome and decompensated heart failure. Coronary angiography demonstrated severe multivessel coronary artery disease, including a long right coronary artery lesion with extensive IVUS attenuation. Given the high risk of distal embolization, PCI was performed using a distal protection device. Drug-eluting stents were successfully implanted, and TIMI flow grade 3 was maintained throughout the procedure without slow-flow or no-reflow. Histopathological examination of debris captured by the distal protection device demonstrated predominantly fibrin- and collagen-rich thrombotic material with macrophage infiltration and no apparent abundant lipid component. The patient experienced an uneventful recovery and was discharged without procedural complications. Conclusion The composition of retrieved embolic debris captured during PCI differed from the expected imaging phenotype. This case highlights the potential discrepancy between intracoronary imaging appearance and embolized material and underscores the multifactorial nature of coronary slow-flow and no-reflow. Careful interpretation of IVUS attenuation and embolic pathology is warranted when assessing procedural risk.