Author + information
- Pamela S. Douglas, MD∗ ( and )
- Melissa A. Daubert, MD
- ↵∗Address for correspondence:
Dr. Pamela S. Douglas, Duke Clinical Research Institute, 7022 North Pavilion, Duke University Medical Center (DUMC), P.O. Box 17969, Durham, North Carolina 27715.
“It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness.”
—A Tale of Two Cities, Charles Dickens (1)
Such sentiments can be applied to the state of diagnostic testing approximately a decade ago, as well as the current era of cardiovascular imaging. In the early part of the 21st century, the rapidly increasing use of diagnostic testing and the associated costs were unsustainable, and thus, gave rise to the development of appropriate use criteria for cardiovascular imaging and contributed to the popularization of comparative effectiveness research in cardiovascular disease (2,3). In patients with acute chest pain presenting to the emergency department (ED), several recent randomized trials have studied the feasibility, safety, and efficacy of anatomic imaging with coronary computed tomography angiography (CTA) compared with the standard of care, which was typically functional stress testing (4–7). In all of these studies, coronary CTA was found to be a feasible and safe alternative to functional stress testing for the evaluation of acute chest pain. Anatomic testing with coronary CTA resulted in the detection of coronary artery disease (CAD) in a greater number of patients but was associated with more radiation than all but nuclear stress testing (4–6). In some studies, coronary CTA was associated with greater downstream testing and coronary revascularization but also served as an effective gate-keeper to the catheterization laboratory by lowering the rate of cardiac catheterizations without obstructive disease (5–7). Finally, coronary CTA has also been shown to reduce ED length of stay, be cost-neutral or even decrease cost, and potentially lower recidivism rates compared with standard care (4–7).
In this issue of iJACC, Levsky et al. (8) present a variation on this comparative effectiveness theme in which they compare coronary CTA with stress echocardiography for the evaluation of acute chest pain. To the best of our knowledge, this is the first randomized trial to directly compare coronary CTA and stress echocardiography in the ED. The authors found that in low- to intermediate-risk patients evaluated during weekday daytime hours, stress echocardiography resulted in fewer hospital admissions, a shorter ED length of stay, and a shorter hospital length of stay (among patients who were admitted), compared with patients initially evaluated with coronary CTA. Like previous trials, there was no difference in adverse event rates between the diagnostic modalities; however, as expected, coronary CTA was associated with higher radiation exposure than stress echocardiography. This study was particularly notable for the diverse population enrolled (87% ethnic minorities), unique assessment of the patient’s subjective experience, and extended follow-up period. Additionally, this study performed functional testing after a single negative troponin test, albeit at least 8 h after symptom onset. This effectively eliminated the up-front time advantage of coronary CTA, which routinely only requires 1 negative troponin test, whereas functional testing is typically not performed until serial troponin assessments are negative.
The primary endpoint of “hospitalization for any cause after initial presentation” might have favored stress echocardiography, at least in the short term, for 2 main reasons. First, more patients receiving coronary CTA were hospitalized for noncardiac causes than those evaluated with stress echocardiography, likely because the rate of incidental findings is higher with coronary CTA than with stress echocardiography; however, this is not necessarily a disadvantage. Second, coronary CTA can detect both obstructive and nonobstructive CAD, but stress echocardiography would be expectedly negative in patients without functionally significant stenoses, even though they could still have underlying CAD. Although it was not explicitly stated, the authors imply that coronary CTA resulted in a higher rate of CAD diagnosis than stress echocardiography, which could explain the higher rates of hospital admission in the coronary CTA group for “further assessment of CAD.” The ability of coronary CTA to detect nonobstructive CAD, which also has important prognostic significance, is thought to lead to intensification of medical therapy, a factor credited with reducing the rate of myocardial infarction (9). However, although lipid-lowering therapy and beta blockade were significantly increased in the coronary CTA arm, this did not translate into a difference in outcomes in this trial, likely because the small size resulted in insufficient power to show a difference in this clinical endpoint. Moreover, the rate of all-cause hospitalization was similar between modalities over the complete follow-up period (approximately 2 years), which suggests that the early advantage of stress echocardiography was later negated.
This study was well conducted and brings attention to stress echocardiography, an often underutilized testing option that is attractive given its lack of radiation and relatively low cost. Additionally, although there were no serious complications because of the initial diagnostic testing in either group, and the median scores for patients’ subjective experience did not significantly differ between modalities, there was a higher rate of patient dissatisfaction about examination length or positional discomfort in the coronary CTA group than with stress echocardiography. The computed tomography technology used in this study (single-source 64-detector-row scanner) is the minimum required for the performance of coronary CTA, and newer multidetector scanners that can perform coronary CTA in a fraction of the time might have provided a reduction in radiation dose and been better tolerated because of quicker scan times and shorter breath holds. Furthermore, coronary CTA can be performed in combination with a physiological assessment, such as computed tomography perfusion or fractional flow reserve, but to date, no study has compared this with functional testing. The addition of physiological data might reduce the duplicative testing in patients initially evaluated with coronary CTA, which was seen in this study and in previous studies. Additionally, the authors note that high-sensitivity troponin testing is anticipated to dramatically change the algorithms for the evaluation of acute chest pain; if this is true, then additional diagnostic testing might not be needed. However, a large prospective trial would be required to demonstrate the safety of such a strategy.
A safe and efficient triage strategy for patients with possible acute coronary syndrome is highly desirable, but taken together, the evidence suggests that no one test is best for evaluating all, or even the majority, of the 8 to 10 million patients presenting to the ED each year with acute chest pain (10). Instead, different tests yield different diagnostic information, and their value depends on a multitude of factors: 1) goals of testing (e.g., for immediate rule out of acute coronary syndrome vs. determining chest pain etiology vs. establishing a CAD diagnosis and guiding long-term management); 2) individual risk factor profiles; 3) patient preference/ability; 4) test availability and local expertise; and 5) safety (e.g., cumulative radiation exposure). As medicine moves away from a 1-size-fits-all approach to one characterized by personalized decision making based on multiple data sources, perhaps imaging should follow suit. To do this, we need to move past the polarizing and overly simplistic anatomic versus functional debate to develop and adopt the principles of precision testing. That would be the best of times.
↵∗ Editorials published in JACC: Cardiovascular Imaging reflect the views of the authors and do not necessarily represent the views of JACC: Cardiovascular Imaging or the American College of Cardiology.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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