Similarly, the writing committee considered a measure assessing rates of blood transfusion after PCI. This was not included as a measure because the writing committee felt that it is currently challenging to adequately account for all the factors related to the decision to transfuse patients after PCI, some of which might be related only indirectly to the procedure. Emergency coronary artery bypass surgery after Nallamothu et al. JACC Vol. 63, No. 7, 2014 ACC/AHA/SCAI/AMA-PCPI/NCQA February 25, 2014:722 45 PCI was also considered as a measure, but in an era of widespread use of stents, the incidence is extremely small, which would make it an unreliable measure. Finally, a measure of periprocedural infarction based on cardiac biomarkers after PCI was considered. However, stan- dardized collection of cardiac biomarkers after PCI is still a variable practice, and this strongly in uences rates of peri- procedural infarction. Given these concerns and that stan- dardized collection of cardiac biomarkers after PCI is not a Class I recommendation in recent PCI guidelines, this measure was not included. Three outcome measures, in particular, were considered strongly by the writing committee, and these are reviewed in detail in the following sections. The writing committee considered a measure of assess- ment of angina. Given that one of the primary reasons for performing PCI is to reduce angina, the concept of assessing anginal class in a structured way before PCI, and reassessing it in the same way after PCI, has intuitive ap- peal. However, the writing committee noted several chal- lenges. First, it was recognized that angina/ischemia can present in different ways, and there was little agreement on how to account for unusual symptoms presenting as an anginal equivalent. Second, it was recognized that rigorous, standardized anginal class assessment (e.g.