Microvessel Rupture and Intraplaque Hemorrhage.

BACKGROUND: Intraplaque hemorrhage (IPH) is an important mechanism of plaque progression and destabilization, primarily attributed to disruption of fragile intraplaque microvessels; however, in vivo demonstration of this process remains limited. CASE SUMMARY: A 56-year-old woman presented with unstable angina. Coronary computed tomography angiography demonstrated a noncalcified, low-attenuation plaque with positive remodeling in the proximal right coronary artery. Optical coherence tomography (OCT) revealed intraplaque microvessels, a crescent-shaped hypointense plaque region consistent with IPH, and findings suggestive of microvessel disruption. The lesion was successfully treated with drug-eluting stent implantation. DISCUSSION: This case highlights the value of OCT in identifying intraplaque mechanisms of acute coronary syndrome beyond classical intimal disruption and provides in vivo findings suggestive of microvessel disruption associated with IPH. TAKE-HOME MESSAGES/LEARNING OBJECTIVES: IPH resulting from disruption of fragile intraplaque microvessels may represent an underrecognized mechanism of acute coronary syndrome. OCT enables detailed assessment of intraplaque architecture and may provide mechanistic insights beyond angiographic evaluation.