Intravascular ultrasound for recognition of atherosclerotic plaques and plaque composition. Current state of the diagnostic value

: Coronary atherosclerosis including acute coronary syndrome (ACS) is the leading cause of death in the western world and in the majority of patients is caused by plaque rupture in flow-limiting and non-flow-limiting angiographically intermediate stenoses. Histopathologic analyses have shown the relationship of plaque composition to acute clinical events and therefore to the vulnerability of coronary lesions. Knowledge of remodeling processes of the coronary artery has focused interest on non-flow-limiting lesions of the coronary tree. Intravascular ultrasound (IVUS) can demonstrate discrepancies between the extent of coronary atherosclerosis and angiographic imaging by in vivo plaque imaging. In addition the spectral analysis of IVUS-derived radiofrequency (RF) data enables more precise analysis of the plaque composition and plaque type.As IVUS is best able to assess stent underexpansion and malapposition the guidance of catheter-based coronary interventions plays a major role in angiographically unclear lesions even in the drug-eluting stent era. In the field of percutaneous coronary interventions (PCI) IVUS can influence the therapy and therefore optimize the stratification of patients.In terms of secondary prevention it is of great clinical importance to detect progression of coronary artery disease and moreover to predict coronary lesions with significant progression up to ACS. Coronary angiography and clinical parameters are poor surrogates to predict future events in a broad cohort of patients after PCI. In addition non-invasive imaging fails to identify coronary plaques with potential rupture and subsequent ACS. This highlights the need to identify potentially high risk lesions. However, prospective studies with IVUS-RF imaging to detect lesions that are considered to be prone to rupture showed no evidence for catheter-based invasive treatment of a non-flow-limiting high risk plaque.In the future the integrated combination of multiple technologies (e.g. IVUS-RF and optical coherence tomography) can further improve the accuracy of the analysis of high risk lesions.