The appropriate use criteria: Improvements for its integration into real world clinical practice.

The purpose of this position statement is to suggest ways in which future appropriate use criteria (AUC) for coronary revascularization might be restructured to: (1) incorporate improvement in quality of life and angina relief as primary goals of therapy, (2) integrate the findings of recent trials into quality appraisal, (3) employ the combined information of the coronary angiogram and invasive physiologic measurements together with the results of stress test imaging to assess risk, and (4) recognize the essential role that patient preference plays in making individualized therapeutic decisions. The AUC is a valuable tool within the quality assurance process; it is vital that interventionists ensure that percutaneous coronary intervention case selection is both evidence-based and patient oriented. Appropriate patient selection is an important quality indicator and adherence to evidence-based practice should be one metric in a portfolio of process and outcome indicators that measure quality.

Validation of scoring system predicting permanent pacemaker implantation after transcatheter aortic valve replacement.

BACKGROUND: Transcatheter aortic valve replacement (TAVR) is being increasingly performed in patients with severe aortic stenosis. Despite newer generation valves, atrioventricular (AV) conduction disturbance is a common complication, necessitating permanent pacemaker (PPM) implantation in about 10% of patients. Hence, it is imperative to improve periprocedural risk stratification to predict PPM implantation after TAVR. The objective of this study was to externally validate a novel risk-stratification model derived from the National Inpatient Sample (NIS) database that predicts risk of PPM from TAVR. METHODS: Components of the score included pre-TAVR left and right bundle branch block, sinus bradycardia, second-degree AV block, and transfemoral approach. The scoring system was applied to 917 patients undergoing TAVR at our institution from November 2011 to February 2017. We assessed its predictive accuracy by looking at two components: discrimination using the C-statistic and calibration using the Hosmer-Lemeshow goodness of fit test. RESULTS: Ninety patients (9.8%) required PPM. The scoring system showed good discrimination with C-statistic score of 0.6743 (95% CI: 0.618-0.729). Higher scores suggested increased PPM risk, that is, 7.3% with score ⩽3, 19.23% with score 4-6, and 37.50% with score ≥7. Patients requiring PPM were older (81.4 versus 78.7 years, P = .002). Length of stay and in-hospital mortality was significantly higher in PPM group. CONCLUSIONS: The NIS database derived PPM risk prediction model was successfully validated in our database with acceptable discriminative and gradation capacity. It is a simple but valuable tool for patient counseling pre-TAVR and in identifying high-risk patients.

Views of Appropriate Use Criteria for catheterization and percutaneous coronary revascularization by practicing interventional cardiologists: Results of a survey of American College of Cardiology Interventional Section members.

OBJECTIVES: The American College of Cardiology (ACC) Interventional Section Council leadership sought to examine the views of interventional cardiologists regarding the practical implementation and the value of the Appropriate Use Criteria (AUC) in their clinical practice. BACKGROUND: The ACC AUC for revascularization were originally intended to assess trends in revascularization patterns by hospitals and physicians to ensure that both under- and over-utilization were minimized. As a quality assurance tool, the AUC were designed to allow physicians to obtain insight into their practice patterns and improve their practice. Recent trends toward tying payment to performance have raised concerns that these criteria will be incorrectly applied to individual patient reimbursement, which is not what they were designed to do. Consequently, the AUC have become controversial, not for their value in quality assessment, but for the manner in which agencies have used the AUC as a tool to potentially deny payment for certain patients. METHODS: Utilizing an online survey, members of the ACC Interventional Section were queried regarding the use of AUC, how they use them, and how they feel utilization impacts the care of patients. RESULTS: We found substantial variability in how the AUC were utilized and concern regarding the value of AUC. Among our findings was that respondents were split (51% vs 49%) regarding the value of AUC to patients and/or their laboratory. CONCLUSIONS: In this article, we discuss the implications of these findings and consider options on how AUC might be made a better-accepted and more impactful tool for clinicians and patients.

Assessing Performance and Quality After Non-ST Segment Elevation Acute Coronary Syndromes.

PURPOSE OF REVIEW: This review summarizes and discusses the evidence base supporting current performance and quality measures used in assessing institutions in their care of patients with non-ST segment elevation acute coronary syndromes (NSTE-ACS). RECENT FINDINGS: Professional societies in the USA and Europe have developed performance and quality measures for NSTE-ACS. These measures are reviewed and updated periodically to reflect the most important evidence from the literature. In the USA, the ACC/AHA Task Force on Performance Measures published the updated 2017 AHA/ACC Clinical Performance and Quality Measures for Adults With ST-Elevation and Non-ST-Elevation Myocardial Infarction. In Europe, the ESC Acute Cardiac Care Association published the 2017 Quality Indicators for acute myocardial infarction. These documents build on guidelines previously developed and published by the two organizations. They include detailed reviews of current and past studies establishing that adherence with guidelines improves clinical outcomes. Both measure sets provide quantitative methodologies to assess program performance. Institutional programs that focus on these validated measures can increase guideline adherence, streamline and standardize care processes, and reduce morbidity and mortality. Performance and quality measures have become a critical part of healthcare today, allowing patients, providers, administrators, and payors to assess patient care objectively. They are also becoming an important component of value-based payment programs. To be fair, and useful, for internal institutional assessment, in comparing different institutions, and for value-based payments, only validated performance measures such as these should be employed.

Use of mechanical circulatory support in patients undergoing percutaneous coronary intervention: insights from the National Cardiovascular Data Registry.

BACKGROUND: Little is known about the contemporary use of intra-aortic balloon pump (IABP) and other mechanical circulatory support (O-MCS) devices in patients undergoing percutaneous coronary intervention (PCI) in the setting of cardiogenic shock. METHODS AND RESULTS: We identified 76 474 patients who underwent PCI in the setting of cardiogenic shock at one of 1429 National Cardiovascular Data Registry CathPCI participating hospitals from 2009 to 2013. Temporal trends and hospital-level variation in the use of IABP and O-MCS were evaluated. No mechanical circulatory support was used in 41 286 (54%) patients, 29 730 (39%) received IABP only, 2711 (3.5%) received O-MCS only, and 2747 (3.6%) received both IABP and O-MCS. At the start of the study period, 45% of patients undergoing PCI in the setting of cardiogenic shock received an IABP and 6.7% received O-MCS. The proportion of patients receiving IABP declined at an average rate of 0.3% per quarter, whereas the rate of O-MCS use was unchanged over the study period. The predicted probability of IABP use varied significantly by site (hospital median 42%, interquartile range 33% to 51%, range 8% to 85%). The probability of O-MCS use was <5% for half of hospitals and >20% in less than one-tenth of hospitals. CONCLUSIONS: In this large national registry, the use of IABP in the setting of PCI for cardiogenic shock decreased over time without a concurrent increase in O-MCS use. The probability of IABP and O-MCS use varied across hospitals, and the use of O-MCS was clustered at a small number of hospitals.

Comparison of percutaneous coronary intervention for previously treated versus de novo culprit lesions in acute myocardial infarction patients: insights from the National Cardiovascular Data Registry.

BACKGROUND: Little is known about percutaneous coronary intervention (PCI) outcomes among patients presenting with an acute myocardial infarction (MI) with a history of prior PCI. Outcomes may differ depending on whether PCI is performed on a previously treated or de novo culprit lesion. METHODS: We examined ST-segment elevation myocardial infarction (STEMI) and non-STEMI patients who underwent PCI in the CathPCI Registry from 2009 to 2012. We used multivariable logistic regression to compare adjusted in-hospital mortality between groups. RESULTS: Among 675,587 MI patients, 147,841 (22%) had a history of prior PCI; these patients were older and more frequently had co-morbid conditions yet had lower adjusted mortality compared with patients undergoing their first intervention (OR = 0.73, 95% CI = 0.70-0.76). Among patients with prior PCI, 50,744 (34%) received intervention to a culprit lesion in a previously treated segment. Compared with patients with de novo culprit lesions, those with previously treated culprits were more likely to present with STEMI, but had lower mortality risk (OR = 0.88, 95% CI = 0.82-0.95) regardless of STEMI or non-STEMI presentation. Among previously treated patients, in-hospital mortality was not significantly different between those with prior drug-eluting versus bare metal stent-treated culprit lesions (OR = 0.95, 95% CI = 0.81-1.12). CONCLUSION: Despite greater co-morbidity burden, MI patients with prior PCI had lower mortality compared with patients undergoing their first intervention. Among patients with prior PCI, patients undergoing PCI to a previously treated culprit lesion were associated with lower mortality than those being intervened for a de novo culprit. A better understanding of these differences will help improve procedural strategies and outcomes of patients undergoing PCI of a previously treated lesion.

Impact of glomerular filtration rate on clinical outcomes after carotid artery revascularization in 11,832 patients from the CARE registry.

OBJECTIVE: The aim of this study was to assess the association of kidney function with carotid artery revascularization outcomes in a large contemporary database. BACKGROUND: Chronic kidney disease (CKD) is associated with increased mortality and adverse cardiovascular events after coronary intervention. There are limited data evaluating the association between CKD and adverse events among patients undergoing carotid artery revascularization procedures. METHODS: The Carotid Artery Revascularization and Endarterectomy (CARE) Registry is a voluntary registry of 168 hospitals. Using data from the CARE Registry, we examined registry patients undergoing carotid artery revascularization by either carotid endarterectomy (CEA) or carotid artery stenting (CAS) from May 2005 through March 2010. Patients were divided into four groups according to their glomerular filtration rate (GFR), as estimated by the Modification of Diet in Renal Disease Study Group equation using preprocedural serum creatinine levels. RESULTS: The analysis included 11,832 patients who underwent carotid revascularization (6,899 CAS and 4,933 CEA). Patients with lower GFR were older, more frequently female, had more comorbidities, including hypertension, dyslipidemia, peripheral arterial disease, diabetes mellitus, chronic lung disease, ischemic heart disease, heart failure, and reduced left ventricular function, and were more likely to undergo CAS than CEA. In the overall population, CKD was associated with higher unadjusted in-hospital and 30-day rates of the combined endpoint of death, stroke, and myocardial infarction and the individual endpoint of stroke. After adjustment for baseline and preprocedural characteristics, CKD was not an independent predictor of adverse events in either CAS or CEA. CONCLUSIONS: Patients with CKD have a greater number of comorbidities and worse unadjusted in-hospital and 30-day outcomes; CKD was not, however, an independent predictor of in-hospital and 30-day outcomes after carotid artery revascularization.

Low diagnostic yield of elective coronary angiography.

BACKGROUND: Guidelines for triaging patients for cardiac catheterization recommend a risk assessment and noninvasive testing. We determined patterns of noninvasive testing and the diagnostic yield of catheterization among patients with suspected coronary artery disease in a contemporary national sample. METHODS: From January 2004 through April 2008, at 663 hospitals in the American College of Cardiology National Cardiovascular Data Registry, we identified patients without known coronary artery disease who were undergoing elective catheterization. The patients' demographic characteristics, risk factors, and symptoms and the results of noninvasive testing were correlated with the presence of obstructive coronary artery disease, which was defined as stenosis of 50% or more of the diameter of the left main coronary artery or stenosis of 70% or more of the diameter of a major epicardial vessel. RESULTS: A total of 398,978 patients were included in the study. The median age was 61 years; 52.7% of the patients were men, 26.0% had diabetes, and 69.6% had hypertension. Noninvasive testing was performed in 83.9% of the patients. At catheterization, 149,739 patients (37.6%) had obstructive coronary artery disease. No coronary artery disease (defined as <20% stenosis in all vessels) was reported in 39.2% of the patients. Independent predictors of obstructive coronary artery disease included male sex (odds ratio, 2.70; 95% confidence interval [CI], 2.64 to 2.76), older age (odds ratio per 5-year increment, 1.29; 95% CI, 1.28 to 1.30), presence of insulin-dependent diabetes (odds ratio, 2.14; 95% CI, 2.07 to 2.21), and presence of dyslipidemia (odds ratio, 1.62; 95% CI, 1.57 to 1.67). Patients with a positive result on a noninvasive test were moderately more likely to have obstructive coronary artery disease than those who did not undergo any testing (41.0% vs. 35.0%; P<0.001; adjusted odds ratio, 1.28; 95% CI, 1.19 to 1.37). CONCLUSIONS: In this study, slightly more than one third of patients without known disease who underwent elective cardiac catheterization had obstructive coronary artery disease. Better strategies for risk stratification are needed to inform decisions and to increase the diagnostic yield of cardiac catheterization in routine clinical practice.

Cardiac biomarker measurement after elective percutaneous coronary interventions in older patients: insights from the National Cardiovascular Data Registry.

BACKGROUND: Guidelines recommend consideration of cardiac biomarker measurement after elective percutaneous coronary intervention (PCI), especially with complex cases or complicated procedures. However, the long-term prognostic implications of biomarker measurement after elective PCI have not been well characterized in older patients. METHODS: We examined 157,825 Medicare patients undergoing elective PCI in the United States from 2004 to 2008 at 711 hospitals in the CathPCI Registry. Clinical characteristics and 1-year mortality risk were studied, stratified by creatine kinase-muscle band measurement. RESULTS: Overall, 26% of patients on elective PCI had postprocedure biomarkers measured. These patients had more complex coronary anatomy and procedures but had similar rates of PCI success and inhospital mortality when compared with patients without biomarker measurement. The treating hospital was a significant factor associated with the likelihood of postprocedure biomarker surveillance. Hospitals that measured creatine kinase-muscle band in ≥ 90% of patients on elective PCI had lower associated 1-year mortality rates (adjusted hazard ratio 0.84, 95% CI 0.75-0.94) compared with hospitals that measured in < 10% of patients. CONCLUSIONS: Among older patients undergoing elective PCI, postprocedure cardiac biomarker measurement occurred infrequently and was concentrated at certain hospitals. Hospitals that routinely measured post-PCI biomarkers were associated with lower long-term mortality compared with hospitals without routine measurement.

Shared Decision-Making in Cardiovascular Practice.

Clinical decisions are optimally made collaboratively, with patients and clinicians working together to review all available information and treatment options. A comprehensive dialogue that identifies and brings into focus individual patient goals within the context of the evidence base is the ideal approach. Shared decision-making (SDM) is essential to making choices about treatment preferences and characterizes the optimal practice of evidence-based medicine and good patient care. By supporting patient autonomy and engagement, the patient and family become partners in their health care. Decisions surrounding whether or not to proceed with diagnostic and therapeutic procedures after fully discussing appropriate alternatives are best made considering both the evidence base and patient goals. The central feature of SDM is that a clinician and a patient engage in a dialogue to jointly make decisions, with reciprocated sharing of information that both find beneficial to reach the best decision. SDM entails much more than patient education or informed consent: there must be bidirectional transfer of knowledge, discussion of patient preference, and a process of deliberation reaching consensus. Patient decision aids have been shown to improve patient understanding of options and risks, enhance the patient's involvement, and focus their comprehension of treatment preferences. Patient decision aids also may be of value in strengthening the physician-patient relationship. The need to emphasize SDM should be integrated into the quality process at every level to make it meaningful, not an apparently arbitrary obstacle that requires discovery of a shrewd work-around. A more patient-oriented consideration of the benefits of symptom relief and improved quality of life, in addition to survival and freedom from adverse events, could only be beneficial.

Do postmarketing surveillance studies represent real-world populations? A comparison of patient characteristics and outcomes after carotid artery stenting.

BACKGROUND: To evaluate outcomes after carotid artery stenting in larger real-world populations, the Food and Drug Administration mandated that companies conduct postmarketing surveillance (PMS) studies of approved stent systems. Whether PMS studies are representative of carotid artery stenting in routine clinical practice has not been established. METHODS AND RESULTS: Within the National Cardiovascular Database Registry-Carotid Artery Revascularization and Endarterectomy (NCDR CARE) Registry, we compared patient and procedural characteristics, in-hospital outcomes, and subsequent all-cause mortality after carotid artery stenting in PMS study participants and nonparticipants. We conducted both crude and propensity score-adjusted comparisons for all outcomes between groups. Compared with nonparticipants, participants in PMS studies had lower rates of symptomatic carotid artery disease within the preceding 6 months, prior stroke, and acute evolving stroke at baseline. The PMS study participants had lower unadjusted rates of combined in-hospital death, stroke, or myocardial infarction (2.3% versus 4.1%; P<0.001), driven by lower rates of stroke (1.7% versus 2.7%; P=0.005) and death (0.3% versus 1.4%; P<0.001). Differences in survival persisted after propensity score adjustment (odds ratio, 0.44; 95% confidence interval, 0.21 to 0.95; P=0.04 for in-hospital mortality; and hazard ratio, 0.80; 95% confidence interval, 0.66 to 0.97; P=0.02 for 2-year mortality). Baseline differences in neurological history explained the largest proportion of the difference in outcomes between groups. CONCLUSIONS: Participants in PMS studies for carotid artery stenting have different clinical and procedural characteristics and lower mortality compared with nonparticipants. Extrapolating results from PMS studies of carotid artery stenting to larger real-world settings should be done only with great caution.

Trends and predictors of length of stay after primary percutaneous coronary intervention: a report from the CathPCI registry.

BACKGROUND: Post hoc analyses of clinical trials suggest that certain patients are eligible for early discharge after ST-segment elevation myocardial infarction. The extent to which ST-segment elevation myocardial infarction patients are discharged early after primary percutaneous coronary intervention (PPCI) in current practice is unknown. METHODS: We examined 115,113 patients in the CathPCI Registry to assess temporal trends in length of stay (LOS) after PPCI. Baseline characteristics were compared between patients with LOS ≤2 and >2 days. Predictors of LOS >2 days were determined by logistic regression and adjusted for clustering among centers. Patterns of discharge within 2 days for low-risk patients with no inhospital complications were examined. RESULTS: From January 2005 through March 2009, mean LOS (4.0 ± 3.0 to 3.6 ± 2.7 days) (P for trend <.001) and the proportion of patients discharged after 2 days decreased (72.0%-65.9%), while predicted inhospital mortality risk remained unchanged. Patients with LOS >2 days (n = 77,471; 67.3%) were older and more likely to have had an intra-aortic balloon pump, cardiogenic shock, transfusions, and post-PPCI complications. Of 958 hospitals, 437 (45.6%) discharged at least half of their low-risk patients with no inhospital complications within 2 days. CONCLUSIONS: While the predicted risk profile has remained stable, there has been a significant decrease in LOS after PPCI. Nevertheless, hospitals vary in discharging low-risk and uncomplicated patients early. Discharge within 2 days was associated with specific patient, procedure, and hospital factors. Further study is needed to determine the safety of early discharge among patients undergoing PPCI.

Decreasing Rates of Acute Kidney Injury After Percutaneous Coronary Interventions Through Education and Standardized Order Sets in a Large Tertiary Teaching Center.

Acute kidney injury (AKI) is a common complication of percutaneous coronary interventions (PCI), and it is associated with increased morbidity, mortality, and healthcare costs. Post-PCI AKI is a major quality outcome measured by the National Cardiovascular Data Registry for hospitals that perform PCI. We report the experience of a large, tertiary center with high standardized, post-PCI AKI rates in which we implemented multilevel interventions that included: (1) a multidisciplinary education module for all personnel involved in care of patients undergoing cardiac angiography, (2) a standardized electronic medical record based preprocedure hydration protocol order set for patients undergoing cardiac angiography, and (3) a hydration task list to be completed by the care team the evening before the procedure or prior to admission. All this resulted in a constant decrease of the post-PCI AKI rates in remarkable magnitude, significantly stronger than the national tendency, demonstrating a center-specific behavior.

Trends and Impact of the Use of Mechanical Circulatory Support for Cardiogenic Shock Secondary to Takotsubo Cardiomyopathy.

Data on the trend and impact of mechanical circulatory support (MCS) in patients with Takotsubo cardiomyopathy (TC) are scarce. We evaluated the incidence and outcomes of cardiogenic shock (CS) in TC patients and the trend in use of MCS over time. The National Inpatient Sample from 2005 to 2014 was used to identify patients admitted with TC and those receiving MCS. Multivariate logistic regression was performed to identify predictors of mortality. The Cochran-Armitage test was used for the trend analysis across the years. Admissions for TC showed a linear increase for the study period. From 2005 to 2014 the proportion of TC managed with MCS remained stable, with some yearly fluctuations. Crude in-hospital mortality rate was 2.5% in the patients admitted with TC but was significantly higher in those with CS (15.81% vs 1.68%, p < 0.001). There was no difference in mortality in TC patients with CS, both with and without the use of MCS. However, patients managed with MCS were more likely to be discharged to a skilled nursing facility (31% vs 25.55, p = 0.015) compared with TC patients with CS who were medically managed. The cost of care for patients with TC and CS, managed with MCS was significantly higher than those managed medically ($171K vs $128K, p <0.001). In patients managed with MCS, only sepsis was associated with a higher likelihood of death using multivariate analysis (Odds Ratio 2.538, Confidence Interval 1.245 to 5.172; p = 0.011). In conclusion, the incidence of TC has increased over the years, but the proportion of patients requiring MCS has declined. Crude mortality rate for TC was 2.5%, but was 15.8% in the TC patients with CS. The use of MCS did not lead to improved mortality but was associated with higher cost and increased likelihood of skilled nursing facility discharge.

Outcomes Following Percutaneous Coronary Intervention in Renal Transplant Recipients: A Binational Collaborative Analysis.

OBJECTIVE: To investigate the clinical and procedural characteristics in patients with a history of renal transplant (RT) and compare the outcomes with patients without RT in 2 national cohorts of patients undergoing percutaneous coronary intervention (PCI). PATIENTS AND METHODS: Data from the National Inpatient Sample (NIS) and British Cardiovascular Intervention Society (BCIS) were used to compare the clinical and procedural characteristics and outcomes of patients undergoing PCI who had RT with those who did not have RT. The primary outcome of interest was in-hospital mortality. RESULTS: Of the PCI procedures performed in 2004-2014 (NIS) and 2007-2014 (BCIS), 12,529 of 6,601,526 (0.2%) and 1521 of 512,356 (0.3%), respectively, were undertaken in patients with a history of RT. Patients with RT were younger and had a higher prevalence of congestive cardiac failure, hypertension, and diabetes but similar use of drug-eluting stents, intracoronary imaging, and pressure wire studies compared with patients who did not have RT. In the adjusted analysis, patients with RT had increased odds of in-hospital mortality (NIS: odds ratio [OR], 1.90; 95% CI, 1.41-2.57; BCIS: OR, 1.60; 95% CI, 1.05-2.46) compared with patients who did not have RT but no difference in vascular or bleeding events. Meta-analysis of the 2 data sets suggested an increase in in-hospital mortality (OR, 1.79; 95% CI, 1.40-2.29) but no difference in vascular (OR, 1.24; 95% CI, 0.77-2.00) or bleeding (OR, 1.21; 95% CI, 0.86-1.68) events. CONCLUSION: This large collaborative analysis of 2 national databases revealed that patients with RT undergoing PCI are younger, have more comorbidities, and have increased mortality risk compared with the general population undergoing PCI.

Coronary Stent Healing in Cancer Patients-An Optical Coherence Tomography Perspective.

Objective: This study assessed stent healing patterns and cardiovascular outcomes by optical coherence tomography (OCT) in cancer patients after drug-eluting stent (DES) placement. Background: Cancer treatment, owing to its cytotoxic and antiproliferative effects, could delay stent healing and increase stent thrombosis risk, especially when dual antiplatelet therapy (DAPT) is discontinued early for oncological treatment. OCT can assess stent endothelialization and other healing parameters, which may provide clinical guidance in these challenging scenarios. Methods: This single-center retrospective study enrolled all cancer patients who underwent OCT for assessment of vascular healing patterns after prior DES placement from November 2009 to November 2018. Primary study endpoints were stent healing parameters, including stent coverage, apposition, degree of expansion, neointimal hyperplasia heterogeneity, in-stent restenosis, stent thrombosis, and overall survival (OS). Results: A total of 67 patients were included in this study. Mean time between DES placement and OCT evaluation was 154 ± 82 days. Stent healing matched published values for DES in non-cancer patients (P ≥ 0.063). At 1 year, the OS was 86% (95% confidence interval [CI]: 78-96%) with 0% incidence of acute coronary syndrome. Advanced cancers and active chemotherapies were associated with inferior OS (P = 0.024, hazard ratio [HR]: 3.50, 95% CI: 1.18-10.42 and P = 0.026, HR: 2.65, 95% CI: 1.13-6.22, respectively), while stent healing parameters were unassociated with OS. Forty-one patients (61%) had DAPT duration ≤6 months. Conclusions: Stent healing of contemporary DES appears similar in cancer and non-cancer patients. Cardiovascular risk of cancer patients after DES placement can be managed to facilitate timely cancer therapies, as the underlying malignancy and active chemotherapy ultimately determine survival.

Impact of changes in clinical practice guidelines on assessment of quality of care.

BACKGROUND: Measures for pay-for-performance and public reporting programs may be based on clinical practice guidelines. The impact of guideline changes over time-and whether evolving clinical evidence can render measures based on prior guidelines misleading-is not known. OBJECTIVE: To assess the impact of using different percutaneous coronary intervention (PCI) guidelines when evaluating whether PCI was indicated. RESEARCH DESIGN: PCIs from the National Cardiovascular Data Registry's CathPCI registry performed in 2003-2004 were categorized into indication classes (Class I, IIa, IIb, III), using 2001 American College of Cardiology/American Heart Association guidelines for PCI, the guidelines available at the time of the procedures. The same procedures were recategorized using 2005 guidelines, which reflect the best evidence available to clinicians at the time of PCI. Procedures unable to be categorized were labeled as "Not Certain." SUBJECTS: Patients undergoing PCI for stable or unstable angina in 394 hospitals. MEASURES: Number of procedures changing classification categories using 2001 versus 2005 guidelines. RESULTS: A total of 345,779 PCIs were evaluated. Applying 2001 guidelines, 47.9% had Class I indications; 33.3% Class IIa; 5.9% Class IIb; 3.7% Class III; and 9.2% Not Certain. Applying 2005 guidelines to the same procedures, 25.1% had Class I indications; 57.5% Class IIa; 5.5% Class IIb; 3.7% Class III; and 8.3% Not Certain; 41.1% of procedures changed the classification overall. CONCLUSIONS: The changes in guidelines resulted in a marked shift in whether PCIs done in 2003-2004 were considered indicated. Guideline-based performance measures should be carefully evaluated before implementation to avoid incorrect assessments of quality of care.