Abstract 15504: Application of Combined use of Optical Coherence Tomography and Intravascular Ultrasound for the Diagnosis of Coronary Vulnerable Plaques: A Histological Validation Study
Background: Although optical coherence tomography (OCT) is a high-resolution imaging modality that allows excellent detection of coronary vulnerable plaque (VP), recent studies reported that some stable plaques are misdiagnosed as VP by OCT. This study sought to assess the usefulness of the combined use of OCT and gray-scale intravascular ultrasound (IVUS) for detecting VP.
Methods: IVUS and OCT examinations were performed to identify focal plaques in 52 coronary arteries from 19 autopsy hearts within 6 hours after death. VPs were selected for OCT and IVUS versus histological comparisons. IVUS characteristics of a VP were eccentric lesions with echolucent zones in areas of positive remodeling. OCT characteristic of VP was signal-poor region with diffuse border with cap thickness <65 µm. Plaque meeting both VP criteria was defined as definite-VP. Histological VP was defined as a plaque consisting of a large necrotic core (>2 mm in diameter) with an overlying thin fibrous cap (<65 μ m in thickness).
Results: IVUS and OCT identified 211 focal plaques. A total of 17 plaques (8%) were diagnosed as OCT-derived VP and 39 plaques (18%) as IVUS-derived VP. Only 10 plaques (5%) were categorized as definite-VP. Although the sensitivity for detecting VP was >90% in both modalities, it should be noted that the positive predictive value (PPV) was only 47% for OCT and 18% for IVUS. However, the PPV of VP detection is increased to 80% if IVUS is used in addition to OCT. Although misdiagnosis of VP by OCT often contained histological evidence of microcalcification deposition within smooth muscle cells, this microcalcification was not diagnosed as VP by IVUS (Figure).
Conclusion: Neither modality alone is sufficient for detecting coronary VP. The combined use of OCT and IVUS should be considered a feasible approach for more precise detection of coronary VP in the clinical setting.
- © 2012 by American Heart Association, Inc.