In vivo diagnosis of plaque erosion and calcified nodule in patients with acute coronary syndrome by intravascular optical coherence tomography

Abstract

Objectives: The aim of this study was to characterize the morphological features of plaque erosion and calcified nodule in patients with acute coronary syndrome (ACS) by optical coherence tomography (OCT).

Background: Plaque erosion and calcified nodule have not been systematically investigated in vivo.

Methods: A total of 126 patients with ACS who had undergone pre-intervention OCT imaging were included. The culprit lesions were classified as plaque rupture (PR), erosion (OCT-erosion), calcified nodule (OCT-CN), or with a new set of diagnostic criteria for OCT.

Results: The incidences of PR, OCT-erosion, and OCT-CN were 43.7%, 31.0%, and 7.9%, respectively. Patients with OCT-erosion were the youngest, compared with those with PR and OCT-CN (53.8 ± 13.1 years vs. 60.6 ± 11.5 years, 65.1 ± 5.0 years, p = 0.005). Compared with patients with PR, presentation with non-ST-segment elevation ACS was more common in patients with OCT-erosion (61.5% vs. 29.1%, p = 0.008) and OCT-CN (100% vs. 29.1%, p < 0.001). The OCT-erosion had a lower frequency of lipid plaque (43.6% vs. 100%, p < 0.001), thicker fibrous cap (169.3 ± 99.1 μm vs. 60.4 ± 16.6 μm, p < 0.001), and smaller lipid arc (202.8 ± 73.6° vs. 275.8 ± 60.4°, p < 0.001) than PR. The diameter stenosis was least severe in OCT-erosion, followed by OCT-CN and PR (55.4 ± 14.7% vs. 66.1 ± 13.5% vs. 68.8 ± 12.9%, p < 0.001).

Conclusions: Optical coherence tomography is a promising modality for identifying OCT-erosion and OCT-CN in vivo. The OCT-erosion is a frequent finding in patients with ACS, especially in those with non-ST-segment elevation ACS and younger patients. The OCT-CN is the least common etiology for ACS and is more common in older patients. (The Massachusetts General Hospital Optical Coherence Tomography Registry; NCT01110538).

Keywords: ACS; ECG; MI; NSTE-ACS; NSTEMI; OCT; SCD; ST-segment elevation myocardial infarction; STEMI; acute coronary syndrome; acute coronary syndrome(s); calcified nodule; electrocardiogram; myocardial infarction; non–ST-segment elevation acute coronary syndrome; non–ST-segment elevation myocardial infarction; optical coherence tomography; plaque erosion; plaque rupture; sudden cardiac death.

Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Plaque Classification Algorithm by OCT

Figure 2. Representative Case of “Definite OCT-Erosion”

A 31-year-old man presented with NSTEMI. Angiographic image (upper right) shows a moderate stenosis in the proximal LAD. Serial OCT cross-sectional images from proximal to distal of the culprit lesion indicate that no rupture is detected. Cross-sectional images indicate fibrous plaque (homogeneous high signal region) proximal (A) and distal (D) to thrombus. OCT-erosion is identified as an irregular lumen surface with attached mural thrombus (arrows) overlying a fibrous plaque (B and C). NSTEMI = non-ST-segment elevation myocardial infarction. LAD = left anterior descending coronary artery.

Figure 3. Representative Case of “Probable OCT-Erosion”

A 37-year-old male smoker presented with STEMI. The angiographic image (bottom right) shows a mild stenosis in the proximal LAD. Serial OCT cross-sectional images from proximal to distal of the culprit lesion show absence of detectable rupture (A through D). Underlying plaque morphology is not well visualized due to the presence of residual red thrombus (A, B and C, arrows). OCT images in the distal and proximal segments of the thrombotic lesions show the absence of superficial lipid and calcification (A and D). Abbreviations as in Figure 2.

Figure 4. Representative Case of “OCT-Calcified Nodule”

A 75-year-old male smoker with unstable angina. Coronary angiogram angiography (upper right) demonstrated a complex lesion in the distal right coronary artery. OCT-calcified nodule is identified as a nodular calcification (A) protruding into lumen through a disrupted fibrous cap (arrow heads) overlying superficial calcification with red thrombus (arrows) attached to the disrupted site. The asterisk (*) indicates the guide wire.

Figure 5. Representative Case of “Plaque Rupture”

A 57-year-old man presenting with STEMI was treated with thrombolysis. (A) The coronary angiogram shows the culprit lesion in the mid LAD. Plaque rupture is identified on cross-sectional (B) and longitudinal (C) OCT images by the disrupted fibrous-cap (arrow heads) and a cavity (asterisk) formation inside the plaque. Abbreviations as in Figure 2.

Figure 6. Incidence of Plaque Rupture, OCT-Erosion, and OCT-Calcified Nodule in Patients with ACS

Among the 126 culprit lesions, 55 (44%) lesions were classified as plaque rupture, 39 (31%) lesions were classified as OCT-erosion, 10 (8%) lesions were classified as OCT-calcified nodule, and 22 (17%) lesions were classified as others. OCT-CN = OCT-calcified nodule. ACS = acute coronary syndrome.