Downstream clinical implications of abnormal myocardial perfusion single-photon emission computed tomography based on appropriate use criteria

Population-Based Study on Patterns of Cardiac Stress Testing After Percutaneous Coronary Intervention

BACKGROUND

The appropriate use criteria considers cardiac stress testing within 2 years after percutaneous coronary intervention (PCI) to be rarely appropriate, unless prompted by symptoms or change in clinical status. Little is known about the patterns of cardiac stress testing after PCI in the single-payer Canadian healthcare system, where mechanisms for reimbursement are different from the United States.

METHODS AND RESULTS

Frequency and timing of cardiac stress testing within 2 years of PCI performed between April 2004 and March 2013 in Ontario, Canada, was determined from linked provincial databases. Subsequent rates of coronary angiography and revascularization after stress testing were ascertained. Of the 112 691 patients with PCI, 67 442 (59.8%) underwent at least 1 stress test, with 38 267 (34.0%) undergoing repeat stress testing (ie, >1 stress test) within 2 years. Patients who underwent stress testing were younger, had less medical comorbidities, were more likely to reside in urban areas, and had higher incomes. Spikes in incidence of repeat stress testing were observed at 3 to 4 months, 6 to 7 months, and 12 to 13 months after the prior stress test. Of those tested, only 5.9% underwent subsequent coronary angiography, and only 3.1% underwent repeat revascularization within 60 days of stress testing.

CONCLUSIONS

More than half of all patients undergo cardiac stress testing within 2 years of PCI, with one third undergoing repeat stress tests. Only 1 of 30 tested patients underwent repeat revascularization. These findings reinforce the appropriate use criteria recommendations against routine stress testing after PCI. Further work is needed to aid with the selection of patients most likely to benefit from stress testing after PCI.

Appropriate Use Criteria for Cardiac Computed Tomography: Impact on Diagnostic Utility

BACKGROUND

Appropriate Use Criteria (AUC) guidelines for cardiac computed tomography (CCT) were developed to limit testing to reasonable clinical settings. However, significant testing is still done for inappropriate indications. This study investigates the impact of AUC on evaluability of CCT to determine if inappropriate tests result in a greater proportion of nondiagnostic results.

METHODS

Investigators reviewed the medical records of 2417 consecutive patients who underwent CCT at the University of Ottawa Heart Institute. We applied the 2010 AUC and classified them as appropriate, inappropriate, or uncertain. Unclassifiable tests, as well as those with uncertain appropriateness, were excluded from the final analysis. Cardiac computed tomography results were classified as diagnostic if (1) all coronary segments were visualized, evaluable, and without obstructive stenosis; or (2) obstructive coronary artery disease with greater than 50% diameter stenosis in at least 1 coronary artery. All other test results were considered nondiagnostic.

RESULTS

Of the 1984 patients included in the final analysis, 1522 patients (76.7%) had indications that were appropriate, whereas the remaining 462 (23.3%) were inappropriate. Inappropriate tests resulted in a higher rate of nondiagnostic results compared with appropriate CCT (9.0% vs 6.2%, P = 0.034). Inappropriate tests also had significantly more studies with nonevaluable segments than appropriate tests (24.5% vs 16.4%, P < 0.001) and were more likely to reveal obstructive coronary disease than appropriate CCT (50.5% vs 32.7%, P < 0.001).

CONCLUSIONS

Cardiac computed tomography done for inappropriate indications may be associated with lower diagnostic yield and could impact future downstream resource utilization and health care costs.

Long-Term Prognostic Value of Appropriate Myocardial Perfusion Imaging

Appropriate use criteria (AUC) for single-photon emission computed tomography myocardial perfusion images (SPECT-MPIs) were developed to address the growth of cardiac imaging studies. Long-term prognostic value of AUC in SPECT-MPI has not been tested in existing cohorts. We sought to determine the long-term prognostic value of MPI classified as appropriate. AUC was evaluated in a prospectively designed cohort of patients who underwent clinically indicated MPI. MPI studies were classified based on 2009 AUC for SPECT-MPI. Data regarding downstream coronary angiography (cath), revascularization and all-cause mortality, cardiac death, and nonfatal myocardial infarction (MI) were collected from national registries. Among n = 1,129 MPI scans that received an appropriate grading, 148 all-cause deaths, 109 MIs, 58 cardiac deaths, 152 caths, 113 revascularization procedures occurred over a mean follow-up period of 5.4 ± 1.2 years (0.9% cardiac death rate per year, 1.8% MI rate per year). Most of the scans were low-risk normal MPI scans (summed stress score ≤3; 74.1%). An abnormal scan was associated with higher rates of MI (19.5% vs 6.2%, hazard ratio 1.72, p = 0.017) and cardiac death (13.4% vs 2.3%, hazard ratio 2.12, p = 0.016). In conclusion, MPI scans classified as appropriate have long-term prognostic value, despite a high proportion of low-risk scans. This provides support for clinicians to consider the use of appropriate grading in addition to MPI scan results in patient management.

Outcomes after inappropriate nuclear myocardial perfusion imaging: A meta-analysis

BACKGROUND

The relationship between inappropriate MPI and cardiovascular outcomes is poorly understood. We sought to systematically review the literature on appropriate use criteria (AUC) for MPI, including temporal trend of inappropriate testing and resulting cardiovascular outcomes.

METHODS

We searched the MEDLINE database for studies related to AUC and MPI. The co-primary outcomes were abnormal test results and the presence of cardiac ischemia. Random effects odds ratios (OR) were constructed using DerSimonian-Laird method.

RESULTS

A total of 22 studies with 23,443 patients were included. The prevalence of inappropriate testing was 14.8% [95% confidence interval (CI) 11.6%-18.7%]. Inappropriate MPI studies were less likely to be abnormal (OR 0.41 95% CI 0.35-0.49, P < .0001) and to demonstrate ischemia (OR 0.40, 95% CI 0.24-0.67, P < .0001) compared to appropriate testing. No difference in the rate of inappropriate tests was detected based on the midpoint of the enrollment year (P = .54). The pattern of ordering inappropriate studies was not different between cardiology and non-cardiology providers (OR 0.74, 95% CI 0.51-1.06, P = .10).

CONCLUSION

Inappropriate MPI studies are less likely to yield abnormal results or demonstrate myocardial ischemia. The rate of inappropriate MPI has not decreased over time.

Practice-Level Variation in Outpatient Cardiac Care and Association With Outcomes

BACKGROUND

Utilization of cardiac services varies across regions and hospitals, yet little is known regarding variation in the intensity of outpatient cardiac care across cardiology physician practices or the association with clinical endpoints, an area of potential importance to promote efficient care.

METHODS AND RESULTS

We included 7 160 732 Medicare beneficiaries who received services from 5635 cardiology practices in 2012. Beneficiaries were assigned to practices providing the plurality of office visits, and practices were ranked and assigned to quartiles using the ratio of observed to predicted annual payments per beneficiary for common cardiac services (outpatient intensity index). The median (interquartile range) outpatient intensity index was 1.00 (0.81-1.24). Mean payments for beneficiaries attributed to practices in the highest (Q4) and lowest (Q1) quartile of outpatient intensity were: all cardiac payments (Q4 $1272 vs Q1 $581; ratio, 2.2); cardiac catheterization (Q4 $215 vs Q1 $64; ratio, 3.4); myocardial perfusion imaging (Q4 $253 vs Q1 $83; ratio, 3.0); and electrophysiology device procedures (Q4 $353 vs Q1 $142; ratio, 2.5). The adjusted odds ratios (95% CI) for 1 incremental quartile of outpatient intensity for each outcome was: cardiac surgical/procedural hospitalization (1.09 [1.09, 1.10]); cardiac medical hospitalization (1.00 [0.99, 1.00]); noncardiac hospitalization (0.99 [0.99, 0.99]); and death at 1 year (1.00 [0.99, 1.00]).

CONCLUSION

Substantial variation in the intensity of outpatient care exists at the cardiology practice level, and higher intensity is not associated with reduced mortality or hospitalizations. Outpatient cardiac care is a potentially important target for efforts to improve efficiency in the Medicare population.

Effective risk stratification of patients on the basis of myocardial perfusion SPECT is dependent on appropriate patient selection

Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is commonly used in risk assessment, as an abnormal scan predicts a multifold increase in cardiac risk. Recent studies have showed that application of the appropriate use criteria (AUC) sharpens the prognostic value of SPECT-MPI, while inappropriate use is clinically ineffective and may lead to unnecessary downstream invasive testing and revascularization procedures. In this review, we will discuss recent literature examining the impact of appropriate use on the prognostic value of SPECT-MPI and downstream decision-making. We will also discuss the implications of appropriate use on cost-effectiveness of MPI.

Clinical utility of inappropriate positron emission tomography myocardial perfusion imaging: test results and cardiovascular events

BACKGROUND

Appropriate use criteria for myocardial perfusion imaging (MPI) were developed to categorize scenarios where MPI might be beneficial (appropriate) or not (inappropriate). Few investigations have evaluated the clinical utility of this categorization strategy, particularly with positron emission tomography (PET) MPI.

METHODS AND RESULTS

We conducted this retrospective cohort investigation in a Veterans Affairs (VA) medical center, on predominantly male subjects who underwent PET-MPI. We correlated appropriateness to test result and cardiovascular events. Of 521 subjects, 414 (79.5%) were appropriate, 54 (10.4%) were uncertain, and 53 (10.2%) were inappropriate. PET-MPI was abnormal more often when appropriate or uncertain (28% and 34.6%, respectively, vs 7.7% for inappropriate, P = .003). Among abnormal inappropriate tests, none detected occult ischemia. By Cox regression, summed difference score ≥5 (HR 5.06, 95% CI 2.72-9.44) and an abnormal test result (HR 4.48, 95% CI 2.19-9.14) were associated with higher likelihood of catheterization. Log-rank analysis demonstrated similar likelihood of catheterization when comparing abnormal vs normal test result (P < .0001) and between appropriate, uncertain, and inappropriate tests (P = .024).

CONCLUSIONS

Inappropriate PET-MPI was rarely abnormal, associated with low catheterization rates, and failed to detect occult ischemia for any subjects. The clinical utility of inappropriate PET-MPI is negligible.

Myocardial perfusion imaging determination using an appropriate use smartphone application

BACKGROUND

Inappropriate cardiac imaging has been a significant cost concern and cause of radiation burden to patients.

OBJECTIVE

To assess if a smartphone application (app) based on 2009 Appropriate Use Criteria (AUC) for Cardiac Radionuclide Imaging published by American College of Cardiology would be feasible at the point of order.

METHODS

We evaluated stress myocardial perfusion imaging (MPI) (N = 403) (mean age = 62.23 years; 47.89% males) over a 4 month period using a smartphone app to determine whether the study ordered was Appropriate, Inappropriate, or Uncertain per 2009 AUC. We also monitored the time needed to use the app to determine the level of appropriateness of each stress MPI. The results of the stress MPI were noted.

RESULTS

Of the 403 stress MPIs evaluated, 267 (66.25%) were noted to be Appropriate, 118 (29.28%) were Inappropriate, and 13 (3.23%) were Uncertain, per AUC; 5 (1.25%) remained unclassified. Average time needed to use the app to assess each stress MPI for appropriateness was noted to be 44 (±9) seconds. Non-teaching physicians ordered 70 (38.89%) inappropriate stress MPIs as compared to 20 (23.53%) ordered by physicians on resident teaching service, and 28 (23.33%) by cardiologists (P = .0045). Among inappropriately ordered stress MPIs, 87 (42.65%) were ordered in females as compared to 31 (17.13%) in males (P < .0001). 70 (26.22%) stress MPIs among appropriately ordered were abnormal (reversible ischemia or fixed perfusion defect) as compared to 15 (12.17%) among inappropriately ordered stress MPIs (P = .0032).

CONCLUSION

A free and convenient smartphone app provides an easy-to-use tool to assist physicians in determining the level of appropriateness of stress MPI in a time- and cost-effective manner at the point of order. The smartphone app may have potential to promote the usage of the AUC and possibly aid reduction of healthcare cost and ionizing radiation burden.