Can IVUS-virtual histology improve outcomes of percutaneous carotid treatment?

Several previous studies focusing on comparison between outcomes of carotid artery stenting (CAS) and carotid endoarterectomy (CEA) have put forward conflicting results about the non-inferiority of CAS compared to CEA. Likely outcomes after CAS have been greatly limited by incomplete knowledge of atherosclerotic carotid pathology and probably inappropriate patient selection criteria. In the current practice, only the degree of lumen obstruction is indication to an invasive treatment (CEA or CAS) in symptomatic or asymptomatic patients, but it has been recently demonstrated that histology of carotid plaques also plays a major role. Indeed, plaque morphology and composition seem to influence more importantly outcomes of CAS than those of CEA. Angiography is a poor diagnostic tool to detect the severity and composition of atherosclerotic lesions. Virtual histology (VH) is a new technology incorporated in the latest intravascular ultrasound (IVUS) equipment that allows a validated histological characterization of plaques by performing a spectral, objective and highly-reproducible analysis of the radiofrequency and amplitude data of the ultrasound waves that cross different tissues. This manuscript reports authors' experience with the use of IVUS-VH during CAS. This new technology, by characterizing morphology, extension and histology of carotid plaque, seems to provide important information for confirming percentage of carotid stenosis and judging its embolic potential, tailoring the procedure and guiding the choice of stent and finally for checking stent apposition and complete covering of vulnerable plaques. According to authors' opinion IVUS-VH has the potential to optimize patients' and lesions' selection criteria for CAS in order to improve its outcomes.