Background: We reported that thin cap fibroatheroma is an important predictor for vulnerable plaque (VP) in our preliminary report. In this final report, we evaluated to find clinical and intravascular ultrasound-virtual histology (IVUS-VH) predictors for VP in intermediate lesion.
Methods: Study subjects consisted of 100 lesions in 96 patients (mean 62 years old, 69 males) with intermediate coronary artery lesion, who underwent IVUS-VH examination. Clinical follow up was done in 95 patients (99%) and follow up IVUS-VH were performed in 75 lesions (75%) at mean 8.4±3.1 months.
Results: Mean minimal luminal diameter was 1.64±0.54mm and % diameter stenosis was 43.7±9.2% in total study subjects. Gray scale IVUS data showed that mean minimal luminal area was 5.4±2.2mm2, number of lesion with minimal luminal area (MLA)<4.0mm2 was 31 lesions, and lesion length was 13.6±7.3mm. Fibrous cap atheroma was the most common lesion type (n=43), followed by thin cap fibroatheroma (TCFA, n=28), fibrocalcific atheroma (FCA, n=18), and pathological intimal thickening (n=7). There were 12 lesions in 11 patients showing rapid lesion progression requiring intervention. TCFA showed highest risk for rapid lesion progression (22.2%), followed by FCA (16.7%), fibrous cap atheroma (7.0%) and pathological intimal thickening (0%). Lesion MLA<4.0mm2 showed also higher risk (19.4% vs. 8.8%, p=0.136) than lesion MLA ≥4.0mm2. The risk of rapid lesion progression requiring PCI was highest (26.7%) in those presenting with MLA<4.0mm2 and lesion type of TCFA/FCA, followed by MLA<4.0mm2 or TCFA/FCA (17.0%), and none (0%) in those without the above parameters. The independent predictors for lesion rapid progression were lesion MLA/lesion type (Β=0.236, p=0.001), age (Β=-0.125, p=0.012), proximal reference arterial diameter (Β=0.125, p=0.012) and lesion fibrofatty area (Β=0.056, p=0.047).
Conclusion: This study suggests that lesion type by IVUS-VH, younger age and large proximal reference arterial diameter in intermediate lesion are important predictors for VP as well as MLA<4.0mm2.
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