In unstable patients (eg, severe heart failure or cardiogenic shock, hemodynamically compromising ventricular arrhyth- Table 8. SCAI Expert Consensus Document Requirements for Patient and Lesion Selection and Backup Strategy for Nonemergency PCI by Experienced Operators at Hospitals Without On-Site Cardiac Surgery Patient risk: expected clinical risk in case of occlusion caused by procedure High patient risk: Patients with any of the following Decompensated congestive heart failure (Killip Class 3) without evidence for active ischemia, recent CVA, advanced malignancy, known clotting disorders LVEF 25% Left main stenosis ( 50% diameter) or 3-vessel disease unprotected by prior bypass surgery ( 70% stenoses in the proximal segment of all major epicardial coronary arteries) Single-target lesion that jeopardizes 50% of remaining viable myocardium Lesion risk: probability that procedure will cause acute vessel occlusion Increased lesion risk: lesions in open vessels with any of the following characteristics Diffuse disease ( 2 cm in length) and excessive tortuosity of proximal segments More than moderate calcification of a stenosis or proximal segment Location in an extremely angulated segment ( 90%) Inability to protect major side branches Degenerated older vein grafts with friable lesions Substantial thrombus in the vessel or at the lesion site Any other feature that may, in the operator s judgment, impede successful stent deployment Aggressive measures to open CTOs are also discouraged because of an increased risk of perforation Strategy for surgical backup based on lesion and patient risk High-risk patients with high-risk lesions should not undergo nonemergency PCI at a facility without on-site surgery. High-risk patients with non high-risk lesions: Nonemergency patients with this profile may undergo PCI, but confirmation that a cardiac surgeon and operating room are immediately available is necessary. Non high-risk patients with high-risk lesions require no additional precautions. Non high-risk patients with non high-risk lesions require no additional precautions. 