A successful balloon angioplasty is defined as the reduction of a minimum stenosis diameter to 50% with a final TIMI flow grade 3 (visually assessed by angiography) without side branch loss, flow-limiting dissection, or angio- graphic thrombus.7 For coronary stents, a minimum stenosis diameter of 20% (as visually assessed by angiography) has previously been the clinical benchmark of an optimal angio- graphic result. Given improvements in technology and tech- niques, as well as recognition of the importance of an adequately deployed stent to decrease the risks of stent restenosis and thrombosis,12,228,229 the writing committee concluded that a minimum diameter stenosis of 10% (with an optimal goal of as close to 0% as possible) should be the new benchmark for lesions treated with coronary stenting. As with balloon angioplasty, there should be final TIMI flow grade 3, without occlusion of a significant side branch, flow-limiting dissection, distal embolization, or angiographic thrombus. Problems with determining angiographic success include disparities between the visual assessment and computer-aided quantitative stenosis measurement and self- reporting of success in clinical reports or databases. 3.1.2. Procedural Success A successful PCI should achieve angiographic success with- out associated in-hospital major clinical complications (eg, death, MI, stroke, emergency CABG).7,8 Issues regarding the diagnosis and prognostic implications of procedure-related MI are discussed in Sections 3.3 and 5.10. 3.1.3. Clinical Success In the short term, a clinically successful PCI requires both anatomic and procedural success along with relief of signs and/or symptoms of myocardial ischemia. Long-term clinical success requires that the short-term clinical success remain Levine et al 2011 ACCF/AHA/SCAI PCI Guideline e589 durable and that relief of signs and symptoms of myocardial ischemia persist 9 months after the procedure. Restenosis is the principal cause of lack of long-term clinical success after a short-term clinical success has been achieved. 