In 2009, the American College of Cardiology and American Heart Association published Appropriate Use Criteria for Coronary Revascularization (AUC) to aid patient selection for percutaneous coronary intervention (PCI). The subsequent decline in inappropriate PCIs was interpreted as a success of AUC. However, there are concerns clinicians reclassify nonacute PCIs to acute indications to fulfill AUC. A longitudinal, observational difference-in-differences analysis was performed using administrative claims from US Department of Veterans Affairs (VA) beneficiaries coenrolled in Medicare and from a national random sample of Medicare beneficiaries, undergoing PCI from September 30, 2009, to December 31, 2013. Non-VA hospitals participating in the American College of Cardiology CathPCI registry began receiving AUC reports in 2011, while VA hospitals did not receive reports, serving as quasiexperimental and control cohorts, respectively. We measured the proportion of PCIs coded for acute myocardial infarction, unstable angina, and nonacute coronary syndrome indications by quarter. There were 87 464 and 30 251 PCIs performed in the Medicare and VA cohorts, respectively. In Medicare, proportion of PCIs coded for acute myocardial infarction and unstable angina changed from 31.9% and 12.6% in quarter 4 2009 to 41.0% and 10.5% in quarter 4 2013, an associated 2.00% (95% CI, 1.56%-2.44%; P<0.001) increase per year in PCIs coded for acute coronary syndrome indications. In the VA, proportion of PCIs coded for acute myocardial infarction and unstable angina changed from 26.5% and 15.7% in quarter 4 2009 to 34.3% and 12.3% in quarter 4 2013, an associated 1.20% (95% CI, 0.56%-1.88%; P=0.001) increase per year in PCIs coded for acute coronary syndrome indications. Difference-in-differences modeling found no statistically significant change in PCI coded for acute indications between Medicare and VA, pre- and post-AUC reporting. After introduction of AUC assessments and reporting, we observed comparable increases in coding for acute myocardial infarction and corresponding decreases in coding for unstable angina and nonacute coronary syndrome indications among national cohorts of Medicare and VA enrollees. The provision of appropriate use reporting did not appear to have a substantial impact on the proportion of PCIs coded for acute indications during this study period.