Identifying Stable Chest Pain Patients With Minimal Testing Value
What is the utility of a risk tool developed to use only pretest clinical data to identify patients with chest pain with normal coronary arteries and no clinical events during follow-up?
This was a secondary analysis of a randomized, comparative effectiveness trial (PROMISE [Prospective Multicenter Imaging Study for Evaluation of Chest Pain]), which included stable, symptomatic outpatients without known coronary artery disease (CAD) referred for noninvasive testing. Patients were randomized to receive coronary computed tomography angiography (CCTA) versus functional testing. A low-risk tool was developed and internally validated from 4,631 patients receiving CCTA as their initial test, with a median follow-up of 25 months. Logistic regression analysis was used to evaluate pretest variables to determine factors associated with minimal risk using a two-thirds random sample for model derivation (n = 3,087) and a one-third sample for testing and validation (n = 1,544). The model was then applied to the CCTA and functional testing arms, and test results and event rates were ascertained.
A total of 1,243 of 4,631 patients (26.8%) were in the minimal-risk cohort. The final minimal-risk model included 10 clinical variables that together were correlated with normal CCTA results and no clinical events (C statistic = 0.725 for the derivation and validation subsets; 95% confidence interval, 0.705-0.746): younger age; female sex; racial or ethnic minority; no history of hypertension, diabetes, or dyslipidemia; family history of premature CAD; never smoking; symptoms unrelated to physical or mental stress; and higher high-density lipoprotein cholesterol level. Across the entire PROMISE cohort, this model was associated with the lowest rates of severely abnormal test results (1.3% for CCTA; 5.6% for functional) and cardiovascular death or myocardial infarction (0.5% for a median of 25 months) among patients at the highest probability (10th decile) of minimal risk.
The authors concluded that a clinical tool using readily available pretest variables identifies minimal-risk patients, for whom deferred testing may be used.
This study reports that a clinical tool using readily available pretest variables including risk factor profile, symptom characteristics, and lipid values identifies one-quarter of stable, symptomatic outpatients with suspected CAD who currently have an indication for noninvasive testing, but are at low risk for cardiac events. A strategy of deferred testing for such patients would be very reasonable in these individuals because the benefits of testing are likely to be low and would avoid unnecessary testing. The current risk score, along with other scores such as the Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter Registry (CONFIRM) risk score and the European Society of Cardiology risk scores, appears to provide useful prognostic information, but needs to be validated in larger real-world populations.
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