Plaque Characteristics and Ruptured Plaque Location according to Lesion Geometry in Culprit Lesions of ST-Segment Elevation Myocardial Infarction

BACKGROUND AND OBJECTIVES The correlations between plaque characteristics and plaque rupture location according to segmental lesion analysis have not been well defined. The aim of this study was to assess those characteristics of ST-segment elevation myocardial infarction (STEMI) culprit lesions according to segmental lesion geometry using virtual histology intravascular ultrasound (VH-IVUS). METHODS Sixty single discrete lesions found in the left anterior descending (LAD) coronary arteries of 60 patients with STEMI were included. Each lesion was divided into 3 segments based on lumen area (LA) index, calculated by dividing the lesion LA by the reference LA. RESULTS Among the 3 segments, the mid-segment showed the highest proportion of necrotic core (NC; proximal, mid-, and distal segments: 20.9±11.8%, 22.7±11.3%, and 17.5±11.2%, respectively, p=0.044). VH-IVUS-derived thin-cap fibroatheroma (VH-TCFA) was also more frequently found in the mid-segment than in proximal and distal segments (36.7%, 58.3%, and 16.7%, p<0.001). The mid-segment also showed the highest prevalence of plaque rupture (45.0%, 78.3% and 11.7%, p<0.001) and thrombus (61.7%, 95.0%, and 41.7%, p<0.001) compared to proximal or distal segments. When the lesions were divided into 2 groups according to the median value (4.0 mm²) of minimum lumen area (MLA), plaque rupture at the distal segment was observed only in high MLA lesions (23.3% vs. 0.0%, p=0.011). CONCLUSION Analysis of longitudinal lesion geometry using the LA index can be useful in evaluating plaque vulnerability and the incidence of plaque rupture and thrombus in STEMI patients.