The past several decades have witnessed remarkable advances in medical care, including cardiac imaging. This rapid pace of technological development has provided a wealth of diagnostic and therapeutic tools that have impacted both quality and longevity of an individual’s life.^1,2 Particularly notable are the advances in cardiac imaging, which have revolutionized how patients are diagnosed and treated, enhancing the sensitivity and specificity for the detection of ischemic heart disease and related these results to patient outcomes, thereby resulting in an impact on survival and quality of life.

However, the exuberance for nuclear cardiology, including single-photon emission tomography myocardial perfusion imaging (SPECT MPI) and positron emission tomography (PET), has resulted in a dramatic increase in its use and has contributed to the spiraling costs of health care cost.^3,4 Furthermore, unnecessary testing may result in additional diagnostic tests and potentially unjustified therapeutic intervention, further escalating costs but also potentially impacting on patient health. Furthermore, the use of nuclear cardiology procedures exposes patients who do not need the testing to avoidable risks, as related to ionizing radiation and stress testing.

The Medicare Payment Advisory Commission (Med-PAC) found that the rate of medical imaging between 1999 and 2002 far exceeded other medical services, with an annual increase by 10.1% during this time period (Fig. 13-1).^2,4 Although it was concluded that no determination of inappropriateness was possible to be made due to lack of credible data,⁴ concern was raised as to the possible performance of unnecessary testing, which may have included financial motivation on the part of the providers. In addition to the excessive growth rate, SPECT/PET utilization demonstrated wide geographic variability across the United States, suggesting that differences in the volume of stress imaging procedures were unlikely a consequence of demographics or the prevalence of comorbid conditions alone,^2,7 as these data were corrected for disease severity. Possible contributing factors included the nonuniform distribution of specialized imaging centers, self-referral practice at specific centers, and variances in the understanding of the medical literature.²

Based on the concerns of overuse and misuse noted above, providers, regulators, and payers raised concern about overuse and misuse of radionuclide imaging, especially with regard to the negative economic consequences.^2,5 In response to this and in an effort to reduce spending, health plans began to use radiology benefits management (RBM) companies to act as procedural governors by developing mechanisms to constrain the exponential growth of imaging and limit associated costs.^2,3 The most common used programs included provider exclusion from imaging network and prior notification and precertification.^1,2 These RBM programs reflected a contract with payers and usually functioned with a model based on incentives to reduce volume and costs even though there was little evidence for the improvement of quality of care. The rules that governed the RBM were not necessarily literature based and often lacked transparency in informing providers of why a test was denied. This process varied from one RBM/health plan to another and caused delays in patient care, increased provider and staff work, and led to increased inefficiency. The mere presence of these onerous programs underscored the need for improved guidance regarding optimal patient selection for specific procedures.^6,7

Appropriate Use Criteria

In response to fiscal pressures and with the goal of optimizing test/patient selection to improve the utilization of cardiovascular procedures in an efficient and contemporary fashion,^1,3 appropriate use criteria (AUC) were developed by several organizations, including the American College of Cardiology Foundation (ACCF) and the American Society of Nuclear Cardiology (ASNC).^8–10 The first set of AUC was released in 2005, focused in the indications of cardiac radionuclide imaging¹¹ with an emphasis on the performance of the right test for the right patient at the right time. The appropriateness of a cardiovascular procedure or test is based on the definition showed in Table 13-1. A revised and expanded version of the AUC for radionuclide imaging was published in 2009.¹² However, the latest criteria were in the form of a multimodality testing document for use with stable ischemic heart disease published in 2013. The indications and ranking for SPECT and PET imaging were intended to replace the prior AUC documents for stable ischemic heart disease scenarios.¹⁶ The goal of these 2013 multimodality AUC was to determine which testing modalities, if any, are reasonable for a specific indication. Importantly the new AUC introduced new definitions for categories of appropriate use, which include “may be appropriate” and “rarely appropriate” replacing the prior terminology of “uncertain” and “inappropriate” (Table 13-2).¹ However, original and revised definitions of appropriate use should not be used interchangeably as each set of documents was created independently and the raters of the scenarios were asked to utilize the specific definitions for these terms.

Although the 2009 and 2013 multimodality AUC ratings were similar for most indications, Table 13-3 shows the differences of appropriateness categorization between the 2009 radionuclide imaging AUC and the 2013 multimodality AUC.

AUC Methodology

How the ratings for appropriate use were developed is important, in order to understand that there is a rigorous methodology behind these criteria. The methods for AUC have evolved since the first publication in 2005, but the process remains based in the application of the validated, prospectively based modified Delphi approach and previously published UCLA/RAND Appropriateness Method (Fig. 13-2).^13,14 Following the selection of a topic, and determination of definitions and assumptions, a writing group is created, clinical scenarios, definitions, and assumptions are created, which then undergo an external review. Subsequently, a literature review and guideline mapping is performed, a review panel of more than 30 members then provide feedback, and the writing group revises each of the indications and summary tables that are prepared for the indications raters. The rating panel composed of a variety of individuals with specific backgrounds rate each indication. A second rating is performed after the rating panel has a face-to-face meeting to scores the different scenarios. The final rating is then compiled with the appropriate use score of 7 to 9 as appropriate, 4 to 6 as may be appropriate, and 1 to 3 as rarely appropriate.¹⁵ However, only the category of appropriate use is presented as the final rating, so as to avoid artificial comparisons among the testing modalities.

The indications are grouped under common headings in a structured approach, with the implementation of tables for diagnosis and risk assessment, symptomatology, prior testing, previous revascularization, evaluation for a change in clinical status, and consideration for special circumstances. A hierarchic approach of the indications is used to stratify a clinical situation to one of the indications.^3,16 This flowchart is designed to place clinical conditions into a hierarchy to help assess the appropriateness of a test (Fig. 13-3). The indications are not entirely comprehensive and are not intended to be, are meant to identify common clinical scenarios in the evaluation and follow-up of stable ischemic heart disease (SIHD) that could embrace the majority of contemporary practice, attempting to determine which testing modalities, may or may not be reasonable for a specific indication.¹⁶

The new multimodality AUC emphasizes not on which test is best for each indication but rather on whether a specific testing modality is reasonable for a specific indication. Seven different diagnostic procedures are presented including radionuclide imaging, in order to offer aid to clinical decision making for the detection and risk assessment of stable ischemic heart disease. Eighty indications were included in the most recent publication.¹

AUC for Radionuclide Imaging

Indications are often constructed based on pretest probability of CAD or global coronary heart disease (CHD) risk, exercise ability and electrocardiogram (ECG) interpretability (Appendix 13-1). The first subsection focuses on symptomatic patients where the clinicians should estimate the likelihood of coronary artery disease (CAD) before selecting testing based on age, sex and typical or atypical presentation based on the Diamond and Forrester pretest probability of CAD.³⁶ The next subsection is for asymptomatic patients and takes into account the global CHD risk estimating the probability of experience a cardiovascular event over a given period of time. The third subsection is related to newly diagnosed heart failure, evaluation of arrhythmias without ischemic equivalent or prior cardiac evaluation, and syncope without ischemic equivalent.

The next part of the AUC is designed for patients with prior testing, with subsections for patients without previous intervening revascularization, as sequential testing, as follow-up testing in stable patients or with new or worsening symptoms, also includes another section for postrevascularized patients with percutaneous coronary intervention (PCI) or coronary artery bypass grafts (CABG), that are symptomatic or asymptomatic (Appendix 13-2). The third section is for preoperative evaluation of noncardiac surgery in view of the type of surgery, functional capacity, previous cardiac imaging, active cardiac conditions, and clinical risk factors.¹⁶ This mimics the clinical practice guidelines and is discussed in detail in Chapter 16. The final section focuses on the value of testing to determine the exercise level prior to initiation of exercise prescription or cardiac rehabilitation in patients with and without revascularization, or heart failure.