Unprotected Left Main Percutaneous Coronary Intervention: Integrated Use of Fractional Flow Reserve and Intravascular Ultrasound

F or several decades, bypass surgery has been regarded as the treatment of choice for patients with unprotected left main coronary artery (LMCA) disease.1,2 However, because of easy anatomic accessibility and a relatively large vessel caliber, left main percutaneous coronary intervention (PCI) for LMCA disease has become an attractive option for cardiologists.In addition, technical advances in PCI and stent technology have emboldened physicians to test the feasibility of LMCA intervention and, coupled with the widespread availability of drug-eluting stents (DESs), has led to reevaluation of the role of PCI as a viable alternative treatment for unprotected LMCA disease.3 As a result, during the last decade, the prevalence of LMCA stenting has significantly increased worldwide.In addition, several recent large registries 4-13 and randomized controlled trials [14][15][16][17] have demonstrated that LMCA stenting yields mortality and morbidity rates comparable to coronary artery bypass grafting (CABG).Hence, it is timely to now move the discussion forward on how to optimize PCI results, beyond the feasibility and safety issues with LMCA stenting.In this review, we briefly summarize the current status of LMCA stenting and discuss the concept of optimal LMCA stenting through integrated use of fractional flow reserve (FFR) and intravascular ultrasound (IVUS). Current Status of LMCA StentingOn the basis of increasing off-label experiences with stenting and clinical studies, [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] the American Heart Association/ American College of Cardiology 23 and the European Society of Cardiology and the European Association for Cardio-Thoracic Surgery.24 recently updated the PCI guideline for the elective treatment of LMCA stenosis to include class IIa indications with a B level of evidence depending on the anatomical complexity of the coronary artery disease.Therefore, DES implantation is currently considered an alternative option for selected patients with unprotected LMCA disease.Table 1 summarizes key observational studies, meta-analyses, and randomized trials that compare PCI with DES and CABG.[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Detailed guidelines are summarized in Table 2.However, many unresolved technical issues remain, including how to assess the functional significance of intermediate LMCA stenosis and how to optimize procedural outcomes, especially for LMCA bifurcation lesion PCI.In this regard, daily practice has already changed to include more use of FFR and IVUS for LMCA stenting.25,26