Vulnerable or High-Risk Plaque: A JACC: Cardiovascular Imaging Position Statement.

The concept of high-risk plaque emerged from pathologic and epidemiologic studies 3 decades ago that demonstrated plaque rupture with thrombosis as the predominant mechanism of acute coronary syndrome and sudden cardiac death. Thin-cap fibroatheroma, a plaque with a large lipidic core covered by a thin fibrous cap, is the prototype of the rupture-prone plaque and has been traditionally defined as "vulnerable plaque." Although knowledge on the pathophysiology of plaque instability continues to grow, the risk profile of our patients has shifted and the character of atherosclerotic disease has evolved, partly because of widespread use of lipid-lowering therapies and other preventive measures. In vivo intracoronary imaging studies indicate that superficial erosion causes up to 40% of acute coronary syndromes. This changing landscape calls for broader perspective, expanding the concept of high-risk plaque to the precursors of all major substrates of coronary thrombosis beyond plaque rupture. Other factors to take into consideration include dynamic changes in plaque composition, the importance of plaque burden, inflammatory activation (both local and systemic), healing mechanisms, regional hemodynamic pattern, properties of the fluid phase of blood, and the amount of myocardium at risk subtended by a lesion. Rather than the traditional focus limited to the thin-cap fibroatheroma, the authors advocate a more comprehensive approach that considers both morphologic features and biological activity of plaques and blood. This position paper highlights the challenges to the usual concept of high-risk plaque, proposes a broader definition, and analyzes its key morphologic features, the technological progress of plaque imaging (particularly using intracoronary imaging techniques), advances in pharmacologic therapies for plaque regression and stabilization, and the feasibility and efficacy of focal interventional treatments including preemptive plaque sealing.