The natural history of coronary atherosclerotic plaques assessed by serial virtual histology intravascular ultrasound

Abstract

Purpose: Histological plaque composition is a major determinant of the tendency of atherosclerotic lesions to provoke clinical events. Virtual histology intravascular ultrasound (VH-IVUS) offers an opportunity to assess the detailed quantitative information on plaque composition in vivo. The aim of this study was to assess the natural history of coronary atherosclerotic plaques to use serial VH-IVUS (baseline and 6months after a coronary event). Methods: We performed serial (baseline and 6-month follow-up) VH-IVUS studies of proximal nonculprit, untreated lesions (plaque burden ≥40%) from patients with STEMI. Twenty-four patients (25 lesions) were prospectively enrolled. We classified and analyzed the target plaques into five types; pathological intimal thickening (PIT), VH-IVUS-derived thin-capped fibroatheroma (VH-TCFA), thick-capped fibroatheroma (ThCFA), fibrotic plaque, and fibrocalcific plaque. Results: At baseline, 18 lesions were VH-TCFAs; during follow-up, 8 (45%) VH-TCFAs healed, 5 became PITs, 2 became ThCFAs, 1 became fibrotic plaque, and 10 (55%) VH-TCFAs remained unchanged. 2 new VH-TCFAs developed; 1 late-developing VH-TCFA was PIT, and 1 was ThCFA at baseline. Patients with VH-TCFAs that remained VH-TCFAs were younger (59±7.4 vs. 61.38±11.5 years, p=0.036)and had lower baseline LDL-cholesterol (107.1±25.3 vs. 122.1±67 mg/dL, p=0.026). But, baseline VH-IVUS plaque composition did not differ between VH-TCFAs that healed and VH-TCFAs that remained VH-TCFAs. Conclusions: About half of VH-TCFAs healed during 6-month follow-up, whereas new VH-TCFAs also developed.