Echolucent rupture-prone plaques

Routine measurement of echolucency of atherosclerotic plaques, in addition to degree of stenosis, may change clinical practice in the future. Within the context of previous knowledge in this field, we therefore review recent developments in detection and histological characterization of echolucent rupture-prone plaques and risk for ischaemic events associated with them, as well as risk factors and treatment for such plaques.

Plaque echolucency is associated with increased lipid content and macrophage density (and sometimes haemorrhage), whereas fibrous tissue (and sometimes calcification) dominates echo-rich plaques. Echolucent carotid plaques are associated with higher risk for future ischaemic stroke, particularly in previously symptomatic individuals, and possibly with risk for restenosis after endarterectomy as well as myocardial infarction. These plaques also associate with elevated levels of triglyceride-rich lipoproteins (and with reduced levels of HDL), but not with elevated levels of LDL or acute phase reactants. Risk factor intervention may be more beneficial for patients with echolucent plaques than in those with echo-rich plaques, whereas coronary stenting may be less efficient in patients with echolucent plaques.

If it is to be clinically useful, then the ultrasound method must be further improved such that it may accurately detect echolucent rupture-prone plaques in the individual patient. Furthermore, the possible superior benefit from preventive treatments deployed selectively in patients with echolucent plaques must be better documented in large randomized trials. When these two requirements are met, routine measurement of plaque echolucency could change clinical practice with respect to the preventive treatments that are offered to patients with echolucent plaques as compared with those without such plaques.