In this large, contemporary national registry of patients undergoing PCI in the United States, we found that the vast majority of PCIs performed in acute settings were classified as appropriate using standardized appropriate use criteria. In the non-acute setting, however, only 50% of procedures were classified as appropriate, 38% as uncertain, and 12% as inappropriate. Moreover, there was substantial variation in the hospital proportion of inappropriate PCIs in nonacute settings, ranging from 0% to 55%. Collectively, these findings suggest an important opportunity to examine and improve the selection of patients undergoing PCI in the non-acute setting.
Until recently, efforts to adjudicate the appropriateness of PCI have been limited by the lack of standardized criteria. With the development of appropriate use criteria and the presence of national registries such as the NCDR CathPCI Registry, this study extends the observations of prior studies4
by explicitly and prospectively collecting detailed clinical information about the indications for PCI at more than 1000 US hospitals. Importantly, because our assessments of PCI appropriateness were conducted before the NCDR Cath-PCI Registry had presented the data to participating centers, we believe that our findings reflect contemporary practice and provide important benchmarks for future assessments of procedural appropriateness at the national and hospital level.
Most of the nonacute procedures classified as inappropriate were performed in settings in which the benefit of PCI has not been demonstrated. For instance, 98.5% of patients undergoing an inappropriate PCI in the nonacute setting were either asymptomatic or only mildly symptomatic (Canadian Cardiovascular Society angina class I or II), 72% had low-risk ischemia on noninvasive stress testing prior to PCI, and 94% did not have high-risk coronary anatomical findings. Moreover, 96% of patients undergoing an inappropriate PCI were treated with suboptimal antianginal therapy—a finding highlighted in a recent analysis of medical therapy after publication of the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial.13
In , we have outlined the 5 most common appropriate use criteria indications for an inappropriate nonacute PCI.
Although some of the inappropriate procedures may be explained by extenuating circumstances (eg, high-risk coronary anatomical findings not captured in the appropriate use criteria), these factors are expected to be uncommon and should not account for the majority of procedures classified as inappropriate. It is also possible that patient preferences may influence physician decisions about coronary revascularization.14
However, recent studies have found that patients often overestimate the benefits of PCI,15
and most PCIs are performed ad hoc (immediately following diagnostic angiography), which limits the opportunity for informed discussions with patients about the relative benefits and risks of PCI.16,17
Rather, it is likely that clinician factors are responsible for many of these procedures. Our previous finding of substantial variation in rates of agreement in appropriateness assignments (range, 5%–76%) between individual cardiologists and the technical panel of the appropriate use criteria18
further supports this hypothesis. This suggests a need for further education of physicians about procedural appropriateness to improve patient selection in the nonacute setting.
A major finding of this study was that rates of inappropriate PCI varied markedly at the hospital level. Although some degree of inappropriate PCI use may be attributable to limitations in the appropriate use criteria methodology (eg, high-risk coronary anatomical findings or clinical features not captured in the appropriate use criteria),7
it is unlikely that the proportion of such exceptional cases would vary substantially across hospitals. The best-performing hospitals had 6% or fewer of their nonacute PCIs classified as inappropriate, suggesting that a low hospital rate for inappropriate PCIs is achievable. However, 25% of hospitals had at least 1 in 6 of their non-acute procedures classified as inappropriate, which suggests overuse of PCI in these hospitals and an important opportunity for improvement in patient selection. One strategy for improvement might be the development of additional decision tools that can provide physicians performing the diagnostic coronary angiogram with real-time guidance about the appropriateness of proceeding to PCI.
Our findings also point toward new challenges and directions required for assessing the overall appropriateness of PCI. For instance, a substantial number of procedures were performed in nonacute settings in which procedural appropriateness was uncertain. Although 64% of these patients had intermediate or high-risk ischemia on noninvasive testing, only 12% had severe (class III or IV) angina (). The rating of uncertain appropriateness therefore suggests that there were insufficient data for the technical panel of the appropriate use criteria to conclude that the benefits of PCI, compared with medications alone, would justify the risk and cost of PCI for these indications.
Indications with uncertain appropriateness represent gaps in knowledge and underscore the need for future outcomes-based studies to clarify the benefits of PCI. In addition, although our analyses were conducted prior to hospitals’ knowledge about their rates of procedural appropriateness, future studies of procedural appropriateness will need to account for potential “gaming” of key variables used in appropriateness assessments, such as symptom severity. The use of objective and validated patient-centered health status questionnaires to assess angina and routine data audits would help to facilitate the integrity of future appropriateness assessments.
Our study should be interpreted in the context of the following limitations. First, not all hospitals that perform PCI in the United States participate in the NCDR CathPCI Registry. Our analyses, however, were conducted in a patient sample from more than 1000 hospitals, and our results are currently the most complete assessment of practice patterns throughout the United States. Second, while we examined potential overuse of PCI (ie, inappropriate PCI) within the appropriate use criteria, we were unable to evaluate underuse of PCI—another important component of procedural appropriateness.
Third, we excluded nonacute procedures because of unavailable ischemia risk assessment results, which precluded an assignment of procedural appropriateness. Our sensitivity analyses showed that the rate of appropriate PCIs in the nonacute setting would increase only modestly, from 50% to 58%, even if we ascribed high-risk ischemia results to patients with incomplete information on ischemia risk. Conversely, the rate of inappropriate PCIs in the nonacute setting increased to 21% when we ascribed low-risk ischemia to each of these patients. Fourth, it is possible that hospitals may have inflated their rates of appropriate PCI by reporting more severe symptoms and stress test results; however, this is unlikely, because the period of analysis in this study preceded feedback reports to hospitals about their rates of inappropriate procedures.
Fifth, we were able to categorize PCIs in which assessments of fractional flow reserve were used in the evaluation of coronary artery stenoses between 50% and 60%. However, the use of fractional flow reserve in coronary artery stenoses of greater than 60% were not adjudicated in the appropriate use criteria, which may account for some of the procedures excluded because of no ischemia assessment. Lastly, the appropriate use criteria reflect a synthesis of contemporary clinical trial evidence, clinical practice guidelines, and expert opinion. Some PCIs classified as uncertain or inappropriate may be appropriate when considering unique clinical and patient factors (eg, coronary anatomy not covered by the indications); likewise, some procedures classified as appropriate may be inappropriate in a particular clinical situation (eg, patient with limited life expectancy or end-stage renal disease). Although it is possible that certain factors may lead to a reclassification of procedural appropriateness, this is likely to be uncommon and would not explain the substantial variation in rates of inappropriate procedures across hospitals.
In conclusion, in this large national registry, nearly all PCIs performed for acute indications were appropriate. However, for nonacute indications, the rate of inappropriate procedures was 12%, with the majority of these procedures performed in patients with little to no angina or with low-risk ischemia on stress testing. Moreover, there was substantial hospital variation in the rate of inappropriate PCI for nonacute indications. Better understanding of the clinical settings in which inappropriate PCIs occur and reduction in their variation across hospitals should be targets for quality improvement.