Optimizing outcomes during left main percutaneous coronary intervention with intravascular ultrasound and fractional flow reserve: the current state of evidence.

Percutaneous coronary intervention (PCI) is an evolving indication for the treatment of unprotected left main coronary arterial (UMLCA) stenoses in selected individuals. Intravascular ultrasound (IVUS)-guided PCI within the epicardial coronary tree has been shown to improve acute procedural results and subsequent clinical outcomes. Similarly, fractional flow reserve (FFR) is rapidly gaining popularity as a means to guide the coronary interventionalist to embark upon a "physiological-based" revascularization strategy. In light of the emergence of PCI for ULMCA stenoses, the lack of randomized trials has meant that there are no systematic guidelines that advocate the routine use of these adjunctive imaging techniques to optimize procedural and clinical outcomes. Given the potential dire clinical consequences of procedural failure during ULMCA PCI, in this review we systematically address the current level of evidence for the use of FFR and IVUS during the assessment for and undertaking of PCI for ULMCA stenoses. In lieu of the current available level of evidence, we recommend the use of FFR for the assessment of (angiographic indeterminate) isolated ostial or midshaft left main coronary arterial (LMCA) stenoses in patients who are considered more appropriate candidates for coronary arterial bypass grafting. In those patients with distal/bifurcation LMCA lesions and in those with diffuse/distal coronary arterial disease, we strongly recommend the liberal use of IVUS. Furthermore, in those patients considered likely candidates for ULMCA PCI, IVUS remains crucial for assessing the degree of lumen compromise and the extent, distribution, and morphology of plaque as well as for the immediate postprocedural quantification of stent deployment.