To ensure that guidelines remain current, new data are reviewed biannually to determine whether recommendations should be modified. In general, full revisions are posted in 5-year cycles.1 Jonathan L. Halperin, MD, FACC, FAHA Chair, ACC/AHA Task Force on Clinical Practice Guidelines The scope of this focused update is limited to considerations relevant to multivessel percutaneous coronary intervention (PCI) and thrombus aspiration in patients with ST-elevation myocardial infarction (STEMI) undergoing primary PCI. 1.1. Methodology and Evidence Review Clinical trials presented at the major cardiology organizations 2013 to 2015 annual scientific meetings and other selected reports published in a peer-reviewed format through August 2015 were reviewed by the 2011 PCI and 2013 STEMI GWCs and the Task Force to identify trials and other key data that might affect guideline recommendations. The information considered important enough to prompt updated recommen- dations is included in evidence tables in the Online Data Supplement. Consult the full-text versions of the 2011 PCI and for recommendations in clini- cal areas not addressed in the focused update. The indi- vidual recommendations in this focused update will be incorporated into future revisions or updates of the full-text guidelines. 1.2. Organization of the GWC For this focused update, representative members of the 2011 PCI and 2013 STEMI GWCs were invited to participate. Members were required to disclose all RWI relevant to the topics under consideration. The entire membership of both GWCs voted on the revised recommendations and text. The latter group was composed of experts representing cardiovascular medicine, interventional cardiology, electrophysiology, heart failure, cardiac surgery, emergency medicine, internal medicine, car- diac rehabilitation nursing, and pharmacy. The GWC included representatives from the ACC, AHA, American College of Physicians, American College of Emergency Physicians, and Society for Cardiovascular Angiography and Interventions (SCAI). 