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Prevalence and Characteristics of TCFA and Degree of Coronary Artery Stenosis: An OCT, IVUS, and Angiographic Study
Study Questions:
What are the prevalence and characteristics of thin-cap fibroatheroma (TCFA) at different degrees of coronary artery stenosis in patients with coronary artery disease?
Methods:
The authors identified 643 plaques from 255 subjects who underwent optical coherence tomography (OCT) imaging in all three coronary arteries. They were divided into three groups on the basis of angiographic diameter stenosis: Group A (30-49%, n = 325), Group B (50-69%, n = 227), and Group C (>70%, n = 91).
Results:
OCT showed that the absolute number of TCFA was greatest in Group A (n = 58), followed by Group B (n = 40) and Group C (n = 33). However, the relative prevalence of TCFA was higher in Group C (36%) than in Group A (18%) or in Group B (18%) (p = 0.003 and p = 0.002, respectively). Fibrous cap of TCFA was thinner in Group C than in Group A (p < 0.001) or in Group B (p = 0.001). Intravascular ultrasound (IVUS) showed that plaque burden of TCFA was largest in Group C (80.1 ± 7.4%), compared with Group B (67.5 ± 9.4%) and Group A (58.1 ± 8.4%).
Conclusions:
The absolute number of TCFA is 3 times greater in nonsevere stenosis than in severe stenosis. It is, however, twice as likely for a lesion to be a TCFA in a severe stenosis as in a nonsevere stenosis. TCFA in severely stenotic areas had more features of plaque vulnerability.
Perspective:
This study, performed in a predominantly acute coronary syndrome (ACS) cohort, demonstrated that while the absolute number of TCFA was greater in nonsevere stenosis, the severe stenosis was more likely to be a vulnerable plaque. The study is confounded by the inclusion of both stable and ACS patients, and the severe lesions were more often seen in patients with ACS. I suspect that the findings would have been different if a purely stable cohort of patients was studied. Among patients with ACS, the concept of multiple vulnerable plaques has been recognized for some time and provides the rationale supporting an early invasive approach. Further research is warranted to assess if revascularization decisions guided by plaque characteristics would help optimize patient outcomes.
Keywords: Prevalence, Coronary Artery Disease, Acute Coronary Syndrome, Plaque, Atherosclerotic, Coronary Stenosis, Tomography, Optical Coherence, Constriction, Pathologic, Cost of Illness
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