Clinical utility and significance of intravascular ultrasound and optical coherence tomography in guiding percutaneous coronary interventions.

Both intravascular ultrasound (IVUS) and optical coherence tomography (OCT) can provide critical information that facilitates pre-interventional lesion assessment and post-interventional stent assessment and both have the potential to influence treatment strategy. Meta-analyses of randomized trials and observational studies comparing IVUS-guided percutaneous coronary intervention (PCI) with angiography-guided PCI revealed that IVUS-guided procedures reduce the incidence of target vessel revascularization, stent thrombosis, and myocardial infarction. Several IVUS criteria have been proposed to optimize stent implantation. Whether these criteria can be directly used to facilitate OCT-guided stent implantation needs to be clarified. Recent studies revealed several IVUS- and OCT-derived predictors of adverse events during PCI. Attenuated coronary plaque on IVUS might be related to deterioration of coronary flow after PCI, whereas tissue characterization on IVUS radiofrequency signal analysis can also detect coronary plaques at high risk for distal embolization. Thin-cap fibroatheroma on OCT has been proposed as a useful characteristic for predicting the no-reflow phenomenon. Furthermore, ostial plaque distribution as assessed by IVUS is reported to be a useful predictor of side-branch occlusion after PCI, whereas the severity of calcified lesions may be better assessed by OCT. Although IVUS and OCT each have inherent strengths and weaknesses, these techniques can complement each other, and selective utilization in appropriate patient subgroups or combined usage is expected to be beneficial during PCI procedures.