Recommendations in the 2013 STEMI guideline with regard to PCI of a non infarct-related artery at a time separate from primary PCI in patients who have spontaneous symptoms and myocardial ischemia or who have intermediate- or high- risk ndings on noninvasive testing (Section 6.3 of that guideline) remain operative. Although several observational studies (19,20) and a network meta-analysis (13) have suggested that multi- vessel staged PCI may be associated with better outcome than multivessel primary PCI, there are insuf cient observational data and no randomized data at this time to inform a recommendation with regard to the optimal timing of nonculprit vessel PCI. Additional trial data that will help further clarify this issue are awaited. Issues related to the optimal method of evaluating nonculprit lesions (e.g., percent diameter stenosis, fractional ow reserve) are beyond the scope of this focused update. 3. ASPIRATION THROMBECTOMY (See Section 5.5.2 of the 2011 PCI guideline and Section 4.2 of the 2013 STEMI guideline for additional recommendations.) The 2011 PCI and 2013 STEMI guidelines (9,10) Class IIa recommendation for aspiration thrombectomy before pri- mary PCI was based on the results of 2 RCTs (29,31,32) and 1 meta-analysis (30) and was driven in large measure by the results of TAPAS (Thrombus Aspiration During Primary Percutaneous Coronary Intervention in Acute Myocardial Infarction Study), a single-center study that randomized 1071 patients with STEMI to aspiration thrombectomy before primary PCI or primary PCI only (29,32). Three multicenter trials, 2 of which enrolled signi cantly more patients than prior aspiration thrombectomy trials, have prompted reevaluation of this recommendation. 