Strategies to Defer Testing for Stable Chest Pain
- In patients with stable chest pain referred for CCTA, five distinct pretest investigation strategies were evaluated to identify which patients would be unlikely to benefit from further cardiac testing.
- A strategy combining coronary calcium score and a weighted clinical likelihood model (CACS-CL) performed best at identifying low-risk patients with no evidence of CAD on subsequent CCTA.
- This suggests that the use of the CACS-CL could effectively defer cardiac testing in low-risk patients.
For patients with stable chest pain, which five distinct pretest probability (PTP) strategies most accurately identify patients who are unlikely to benefit from further cardiac testing?
This was a prospective, observational cohort of 4,207 patients with stable chest pain referred for computed tomography angiography (CCTA). They were assigned to low- and high-risk groups based on five distinct investigation strategies:
- NICE (2016 United Kingdom National Institute of Health and Care Excellence) strategy: Patients with nonanginal chest pain and normal electrocardiographic findings were considered low risk.
- PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) minimal risk tool: Low-risk patients were those with a >60% probability of minimal risk.
- European Society of Cardiology (ESC) 2019 guideline-recommended PTP calculator: Patients with an ESC-PTP <5% were low risk, while those >15% were considered high risk. For the 5-15% population, clinical variables plus the calcium score were included for further assessment.
- CACS strategy (coronary artery calcium score): Low risk was a score of 0, and anything >0 was high risk.
- CACS-CL: A calcium score and weighted clinical likelihood model (incorporating age, sex, symptoms, family history of early-onset coronary artery disease [CAD], smoking, dyslipidemia, hypertension, and diabetes mellitus). Patients with CACS-CL score <15% were considered low risk.
The primary endpoint was the rate of detected obstructive CAD on CCTA, and major adverse cardiac events (MACE). Secondary endpoints included medication changes, invasive coronary angiography (ICA), and coronary revascularization.
For the NICE, PROMISE, ESC, CACS, and CACS-CL strategies, the number of patients categorized as low risk was 22.6%, 29.2%, 41.8%, 46.8%, and 51.4%, respectively. CCTA identified obstructive disease in 27.9%, nonobstructive disease in 30.9%, and no CAD in 41.2% of patients. In a smaller validation cohort of 976 patients, ICA was performed after CCTA to assess its false-positive rate, which was 6%. Median follow-up was 17 months (interquartile range, 12-22 months); 1.9% of patients experienced MACE with 0.3% dying from cardiac causes and 1.6% having nonfatal myocardial infarctions.
The CACS-CL strategy had a much stronger association between risk groups and the presence of obstructive CAD in the high- (51%) versus low-risk groups (6.1%) (odds ratio [OR], 16.00; 95% confidence interval [CI], 13.15-13.47; p < 0.0001) compared to the NICE, PROMISE, ESC, and CACS strategies (ORs 2.9, 5.5, 7.9, and 10.4, respectively). This stronger association was also present between CACS-CL and MACE (hazard ratio, 6.83; 95% CI, 3.63-12.85; p < 0.0001) compared to the other groups (1.9, 2.9, 4.23, and 5.13, respectively).
All five strategies had high sensitivities (85-90%) for identifying obstructive CAD. However, compared with symptom-focused and PTP alone-based strategies, CACS-based strategies, especially when further enhanced by clinical variables, had the greatest specificity (67%), negative predictive value (94%), and positive predictive value (51%). Thus, this strategy most effectively identified patients for whom further cardiac testing could be deferred.
Tools for identifying chest pain patients who are unlikely to benefit from further cardiac testing would be of great value to both cardiologists and emergency room (ER) physicians. This article suggests that a number of different strategies have high sensitivity for identification of patients with obstructive CAD, but that incorporation of a calcium score may add specificity, especially when combined with predictive clinical variables (i.e., CACS-CL).
A number of key questions remain. The first is how these calcium scores were obtained. In the previous article from this group (Zhou J, et al., J Cardiovasc Comput Tomogr 2017:317-23), a non–contrast-enhanced cardiac CT was performed prior to CCTA. How often the CACS would be available to clinicians deciding whether to pursue additional testing or how it might be incorporated into a decision-making algorithm is unclear. The second major question is how generalizable these findings would be to medicine outside of China. Patients in the United States, for example, are not typically referred to CCTA for “stable chest pain,” as this description is reserved for those already known to have CAD. The low rate of MACE suggests that these patients may be more analogous to “undifferentiated chest pain” patients in the ER setting, but further studies applying the CACS-CL prospectively will be required.
Keywords: Angina, Stable, Chest Pain, Computed Tomography Angiography, Coronary Angiography, Coronary Artery Disease, Diabetes Mellitus, Diagnostic Imaging, Dyslipidemias, Hypertension, Myocardial Infarction, Myocardial Ischemia, Myocardial Revascularization, Plaque, Atherosclerotic, Secondary Prevention, Smoking, Vascular Calcification
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