February 25, 2014:722 45 ACC/AHA/SCAI/AMA-PCPI/NCQA performance measures with other ACC/AHA/AMA- PCPI performance measure sets when possible. For example, the writing committee did not explore door-to- balloon time as a performance measure, given that this would overlap with performance measures for acute myocardial infarction already constructed and endorsed by numerous organizations. An example of harmonization within the measure set is the postprocedural optimal medical therapy composite measure in the present docu- ment, which is aligned with the similar National Quality Forum endorsed ACCF facility-level measure. 4. General Discussion 4.1. Process Measures Process measures have several advantages. They are more readily under the control of clinicians than are structural or outcome measures and also are actionable targets for quality improvement. Performance measures of processes are most useful when 1) they are directly linked to improved clinical outcomes through robust evidence, and 2) true gaps in care exist. Expending resources to measure processes that are already conducted at uniformly high rates is not justi ed, particularly when burdensome chart abstraction is required. An acknowledged limitation of process measures is that they might not always indicate how well the process was done. For example, measure 4 (use of embolic protection devices in the treatment of saphenous vein bypass graft disease) measures use of the embolic protection device during PCI but does not capture the technical skill with which it was deployed. We considered including measures assessing technical care processes performed in the cardiac catheterization labora- tory but did not include any such measures because of the lack of feasible, nonsubjective measurement criteria. This should be an area of future investigation. Two areas in which the writing committee tried to advance process measures were in patient selection measures and patient education/shared decision-making measures. 