CABG indicates coronary artery bypass graft; CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; COR, class of recommendation; EF, ejection fraction; LAD, left anterior descending; LIMA, left internal mammary artery; LOE, level of evidence; LV, left ventricular; N/A, not applicable; PCI, percutaneous coronary intervention; SIHD, stable ischemic heart disease; STEMI, ST-elevation myocardial infarction; STS, Society of Thoracic Surgeons; SYNTAX, Synergy between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery; TIMI, Thrombolysis in Myocardial Infarction; UA/NSTEMI, unstable angina/non ST-elevation myocardial infarction; UPLM, unprotected left main disease; and VT, ventricular tachycardia. Levine et al 2011 ACCF/AHA/SCAI PCI Guideline e581 2.2. Revascularization to Improve Survival: Recommendations Left Main CAD Revascularization Class I 1. CABG to improve survival is recommended for patients with significant (>50% diameter stenosis) left main coronary artery stenosis.24 30 (Level of Evidence: B) Class IIa 1. PCI to improve survival is reasonable as an alterna- tive to CABG in selected stable patients with signif- icant (>50% diameter stenosis) unprotected left main CAD with: 1) anatomic conditions associated with a low risk of PCI procedural complications and a high likelihood of good long-term outcome (eg, a low SYNTAX score [<22], ostial or trunk left main CAD); and 2) clinical characteristics that predict a significantly increased risk of adverse surgical out- comes (eg, STS-predicted risk of operative mortality >5%).13,17,19,23,31 48 (Level of Evidence: B) 2. PCI to improve survival is reasonable in patients with UA/NSTEMI when an unprotected left main coronary artery is the culprit lesion and the patient is not a candidate for CABG.13,36 39,44,45,47 49 (Level of Evidence: B) 3. 