Features of Ruptured Plaque vs Thin-Cap Fibroatheroma in ACS
Objectives. The study sought to identify specific morphological characteristics of ruptured culprit plaques (RCP) responsible for acute events, and compare them with ruptured nonculprit plaques (RNCP) and nonruptured thin-cap fibroatheroma (TCFA) in patients presenting with acute coronary syndromes (ACS).
Background. Nonruptured TCFA and multiple ruptured plaques are detected in the same patients with ACS. It remains unknown whether certain morphological characteristics determine rupture of TCFA and subsequently result in ACS.
Methods. We analyzed 126 plaques (RCP = 49, RNCP = 19, TCFA = 58) from 82 ACS patients using optical coherence tomography (OCT) and intravascular ultrasound (IVUS). Fibrous cap thickness was determined by OCT. Plaque burden and lumen area were measured with IVUS.
Results. Fibrous cap was thinner in RCP (43 ± 11 μm) and RNCP (41 ± 10 μm) than in TCFA (56 ± 9 μm, p < 0.001 and p < 0.001, respectively). Plaque burden was greater in RCP (82 ± 7.2%), compared with RNCP (64 ± 7.2%, p < 0.001) and TCFA (62 ± 12.5%, p < 0.001). Lumen area was smaller in RCP (2.1 ± 0.9 mm2), compared with RNCP (4.6 ± 2.3 mm2, p = 0.001) and TCFA (5.1 ± 2.7 mm2, p < 0.001). The fibrous cap thickness <52 μm had good performance in discriminating ruptured plaque from TCFA (area under the curve [AUC] = 0.857, p < 0.001), and plaque burden >76% and lumen area <2.6 mm2 had good performance in discriminating RCP from RNCP and TCFA (AUC = 0.923, p < 0.001 and AUC = 0.881, p < 0.001, respectively).
Conclusions. Fibrous cap thickness is a critical morphological discriminator between ruptured plaques and nonruptured TCFA, while plaque burden and lumen area appear to be important morphological features of RCP. These findings suggest that plaque rupture is determined by fibrous cap thickness, and a combination of large plaque burden and luminal narrowing result in ACS.
Plaque rupture is responsible for two-thirds of acute coronary syndromes (ACS) and sudden cardiac death. Thin-cap fibroatheroma (TCFA), which is characterized by the presence of a large lipid pool with overlying thin fibrous cap measuring <65 μm, is recognized as a precursor for plaque rupture. The PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study from Stone et al. has demonstrated that most event-related TCFA had a larger plaque burden and a smaller lumen area. Both in vivo imaging studies and autopsy studies have reported that nonruptured TCFA and multiple ruptured plaques are simultaneously found in ACS patients and sudden cardiac death cases. However, in vivo data on morphological features, which determine rupture of TCFA and subsequent ACS, is limited due to lack of diagnostic modalities. Optical coherence tomography (OCT) has been widely used for coronary plaque characterization including detection of TCFA and plaque rupture. Intravascular ultrasound (IVUS) is another intravascular imaging modality, which has been used to measure lumen area, plaque burden, and vascular remodeling. In this study, we aimed to analyze OCT and IVUS images of all 3 major epicardial arteries in ACS patients, and compare the morphological characteristics between ruptured culprit plaque (RCP), ruptured nonculprit plaque (RNCP), and nonruptured TCFA. In addition, we also evaluated the optimal cutoff values of plaque characteristics for differentiating these 3 types of plaques.
Abstract and Introduction
Abstract
Objectives. The study sought to identify specific morphological characteristics of ruptured culprit plaques (RCP) responsible for acute events, and compare them with ruptured nonculprit plaques (RNCP) and nonruptured thin-cap fibroatheroma (TCFA) in patients presenting with acute coronary syndromes (ACS).
Background. Nonruptured TCFA and multiple ruptured plaques are detected in the same patients with ACS. It remains unknown whether certain morphological characteristics determine rupture of TCFA and subsequently result in ACS.
Methods. We analyzed 126 plaques (RCP = 49, RNCP = 19, TCFA = 58) from 82 ACS patients using optical coherence tomography (OCT) and intravascular ultrasound (IVUS). Fibrous cap thickness was determined by OCT. Plaque burden and lumen area were measured with IVUS.
Results. Fibrous cap was thinner in RCP (43 ± 11 μm) and RNCP (41 ± 10 μm) than in TCFA (56 ± 9 μm, p < 0.001 and p < 0.001, respectively). Plaque burden was greater in RCP (82 ± 7.2%), compared with RNCP (64 ± 7.2%, p < 0.001) and TCFA (62 ± 12.5%, p < 0.001). Lumen area was smaller in RCP (2.1 ± 0.9 mm2), compared with RNCP (4.6 ± 2.3 mm2, p = 0.001) and TCFA (5.1 ± 2.7 mm2, p < 0.001). The fibrous cap thickness <52 μm had good performance in discriminating ruptured plaque from TCFA (area under the curve [AUC] = 0.857, p < 0.001), and plaque burden >76% and lumen area <2.6 mm2 had good performance in discriminating RCP from RNCP and TCFA (AUC = 0.923, p < 0.001 and AUC = 0.881, p < 0.001, respectively).
Conclusions. Fibrous cap thickness is a critical morphological discriminator between ruptured plaques and nonruptured TCFA, while plaque burden and lumen area appear to be important morphological features of RCP. These findings suggest that plaque rupture is determined by fibrous cap thickness, and a combination of large plaque burden and luminal narrowing result in ACS.
Introduction
Plaque rupture is responsible for two-thirds of acute coronary syndromes (ACS) and sudden cardiac death. Thin-cap fibroatheroma (TCFA), which is characterized by the presence of a large lipid pool with overlying thin fibrous cap measuring <65 μm, is recognized as a precursor for plaque rupture. The PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study from Stone et al. has demonstrated that most event-related TCFA had a larger plaque burden and a smaller lumen area. Both in vivo imaging studies and autopsy studies have reported that nonruptured TCFA and multiple ruptured plaques are simultaneously found in ACS patients and sudden cardiac death cases. However, in vivo data on morphological features, which determine rupture of TCFA and subsequent ACS, is limited due to lack of diagnostic modalities. Optical coherence tomography (OCT) has been widely used for coronary plaque characterization including detection of TCFA and plaque rupture. Intravascular ultrasound (IVUS) is another intravascular imaging modality, which has been used to measure lumen area, plaque burden, and vascular remodeling. In this study, we aimed to analyze OCT and IVUS images of all 3 major epicardial arteries in ACS patients, and compare the morphological characteristics between ruptured culprit plaque (RCP), ruptured nonculprit plaque (RNCP), and nonruptured TCFA. In addition, we also evaluated the optimal cutoff values of plaque characteristics for differentiating these 3 types of plaques.
SHARE
