Abstract 4190: Assessment of the Plaque With Echo Signal Attenuation by Optical Coherence Tomography
Backgrounds. The plaque with echo signal attenuation without calcification (EA) has been reported to be related with worse angiographic and clinical outcome after percutaneous coronary intervention (PCI). We sought to evaluate the plaque morphology with EA by OCT, and to evaluate the relationship between OCT-derived characteristics of the plaque with EA and coronary flow during PCI.
Methods and Results. Ninety-seven lesions with consecutive 89 patients with acute coronary syndrome (ACS n=47, 48%) and stable angina pectoris (SAP n=50, 52%), who underwent both pre- and post-procedural IVUS and OCT imagings, were investigated. EA was defined as showing echo signal attenuation >90 degree for more than 1mm without dense calcification on IVUS. Coronary flow during PCI was evaluated by TIMI flow grade. Thin cap fibroatheroma (TCFA) was defined as lipid rich plaque (>one or more lipid quadrants) with cap thickness <70μm. The plaque with EA was observed in 47 lesions (ACS 25, 48%, SAP 22, 44%, p=0.42). The plaque with EA showed significant association with the presence of TCFA (64% vs. 24%, p<0.01), ruptured plaque (66% vs. 32%, p<0.01), thinner cap thickness of fibroatheroma (74±39μm vs. 115±72μm, p<0.01), and more lipid arc (one or more quadrants; 81% vs. 46%, p<0.01), whereas no significant difference in thrombus detection was observed. After balloon angioplasty, plaque disruption, defined as disruption of luminal surface continuity in a radial direction, was significantly more frequent in the plaque with EA than without EA (68% vs 36%, p<0.05). Transient flow deterioration (TIMI flow grade 0 –2) was observed more frequently in the lesions with EA than in those without (54% vs 27%, p<0.05), whereas achievement of TIMI 3 coronary flow after PCI was similar irrespective of the lesions with or without EA (81% vs 88%, p=0.41).
Conclusion: OCT characterized a plaque with EA as a lesion with lipid rich plaque with relatively thin fibrous cap. Disruption of plaque introduced at PCI may result in reduced coronary flow caused by distal embolization of lipid rich plaque debris.