The Vulnerable Plaque: the Real Villain in Acute Coronary Syndromes

Abstract

The term "vulnerable plaque" refers to a vascular lesion that is prone to rupture and may result in life-threatening events which include myocardial infarction. It consists of thin-cap fibroatheroma and a large lipid core which is highly thrombogenic. Acute coronary syndromes often result from rupture of vulnerable plaques which frequently are only moderately stenosed and not visible by conventional angiography. Several invasive and non-invasive strategies have been developed to assess the burden of vulnerable plaques. Intravascular ultrasound provides a two-dimensional cross-sectional image of the arterial wall and can help assess the plaque burden and composition. Optical coherent tomography offers superior resolution over intravascular ultrasound. High-resolution magnetic resonance imaging provides non-invasive imaging for visualizing fibrous cap thickness and rupture in plaques. In addition, it may be of value in assessing the effects of treatments, such as lipid-lowering therapy. Technical issues however limit its clinical applicability. The role of multi-slice computed tomography, a well established screening tool for coronary artery disease, remains to be determined. Fractional flow reserve (FFR) may provide physiological functional assessment of plaque vulnerability; however, its role in the management of vulnerable plaque requires further studies. Treatment of the vulnerable patient may involve systemic therapy which currently include statins, ACE inhibitors, beta-blockers, aspirin, and calcium-channel blockers and in the future local therapeutic options such as drug-eluting stents or photodynamic therapy.

Tomografía de coherencia óptica

“…Múltiples estudios han demostrado que las placas que más frecuentemente se rompen y dan lugar a síndromes coronarios agudos son aquellas con núcleo lipídico-necrótico grande recubierto por una cápsula fi brosa fi na de menos de 65 micras. Estas han sido denominadas como fi broateroma de cápsula fi na (FACF) 14 . Como dijimos previamente, la resolución axial del IVUS es de 100-150 micras, por lo que no es un método adecuado para evaluar este tipo de lesiones.…”

Carotid and Femoral Atherosclerotic Plaques in Asymptomatic and Non-Treated Subjects: Cardiovascular Risk Factors, 10-Years Risk Scores, and Lipid Ratios’ Capability to Detect Plaque Presence, Burden, Fibro-Lipid Composition and Geometry

“…In turn, plaque geometry (e.g., volume, area) and composition (e.g., lipid content, intraplaque hemorrhage) are determinants of plaque vulnerability (i.e., risk of instability and plaque accident) [8][9][10]. Subjects with vulnerable plaques would have increased risk of CV events [11]. Then, determining plaques presence, atherosclerotic burden and/or quantifying vulnerability based on the geometry and/or composition of the plaque(s) would be of value when planning and implementing specific preventive strategies [9,[12][13][14][15].…”

Three‐Dimensional Subharmonic Aided Pressure Estimation for Assessing Arterial Plaques in a Rabbit Model

“…To predict vulnerability, attempts have been made to assess the risk factors associated with atherothrombotic plaques. Atherothrombotic plaques are mainly composed of a connective tissue extracellular matrix, including collagen, proteoglycans, and fibronectin elastic fibers . Each plaque shows a heterogeneous distribution of these components, which mostly affect the intima, but secondary changes occur in the media and adventitia as well, including growth of vasa vasorum .…”

“…Hence, a vulnerable plaque was defined as a fibrous cap less than 65 μm thick with an infiltrate of macrophages with or without plaque rupture . Also, the cap of a vulnerable plaque is often thinnest at the shoulder region, where macrophages and mast cells accumulate . The core of a vulnerable plaque is known to be soft, which may be more vulnerable to rupture, as it may not be able to resist the imposed circumferential stress .…”

“…Also, the cap of a vulnerable plaque is often thinnest at the shoulder region, where macrophages and mast cells accumulate . The core of a vulnerable plaque is known to be soft, which may be more vulnerable to rupture, as it may not be able to resist the imposed circumferential stress . Other characteristics include active inflammation, endothelial denudation with superficial platelet aggregation, a fissured plaque, and the presence of high‐grade coronary stenosis, as well as a superficial calcified nodule, the presence of plaque hemorrhage, endothelial dysfunction, and positive remodeling of the artery …”