Tool may help identify patients with stable chest pain at minimal risk of clinical events

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Researchers have developed a decision support tool to identify patients with chest pain who have minimal risk of having abnormal coronary arteries and long-term clinical events.

Lead researcher Christopher B. Fordyce, PharmD, MD, MHS, MSc, of the University of British Columbia and the Duke Clinical Research Institute, and colleagues published their results online in JAMA Cardiology on Feb. 15.

The researchers noted that guidelines recommend noninvasive testing for symptomatic patients who are at risk of coronary artery disease, although they mentioned that most of the tests are normal.

“There are millions of stress tests done every year in the United States and many of them are normal,” study author James Udelson, MD, chief of the division of cardiology at Tufts Medical Center, said in a news release. “We thought that if we could predict the outcome of these tests by using information we already had from the patient before the test, we could potentially save the health care system money and save our patients time and worry.”

For this analysis, the researchers evaluated patients who enrolled in PROMISE, a comparative effectiveness trial at 193 community practices and academic medical centers in North America. The patients had no known coronary artery disease and were referred for noninvasive testing for further evaluation from July 27, 2010, to Sept. 19, 2013.

The patients were randomized to an anatomical testing strategy with coronary computed tomography angiography (CCTA) or a functional testing strategy that included exercise treadmill testing, stress echocardiography or stress nuclear imaging. They were followed for a median of 25 months.

The researchers developed their model using patients with normal CCTA results. Of the 4,631 patients in the CCTA group, 1,243 (26.8 percent) had normal results and no atherosclerosis and no revascularization procedures or clinical cardiac events during the follow-up period.

During the model development, the researchers identified 10 pretest clinical variables that independently assessed the probability of patients being categorized as minimal-risk. The variables were: younger age; female sex; racial or ethnic minority; no history of hypertension, diabetes, dyslipidemia or family history of premature coronary artery disease; never smoking; symptoms unrelated to physical exertion or stress; and higher high-density lipoprotein cholesterol.

The model had good discrimination (C-statistic of 0.725) and improved existing risk scores, according to the researchers. They then used the model to develop a pretest decision support tool to help identify patients who would not receive much benefit from testing.

“The ability to identify a subset of intermediate pretest probability patients with stable chest pain who might safely defer noninvasive testing is appealing given concerns about the low yield of testing in current practice and the associated costs,” the researchers wrote. “Studies suggest that the results of most functional stress studies on outpatients with a clinical syndrome of possible ischemia are normal, and nearly all such patients will not experience an untoward clinical event.”

The study had a few limitations, according to the researchers, including that the results might not be generalizable to higher-risk groups with a greater prevalence of disease or incidence of events or people who did not consent to participate in a clinical trial. They also mentioned that the model should be further validated in other independent data samples. In addition, they noted that the tool is not intended as a decision support to test or not test patients but is meant as an aid to quantify minimal risk. They wrote that the tool could potentially identify patients who are unlikely to benefit from proceeding directly to noninvasive testing.

“In this age of accountable care, there has been a lot of attention focused on trying to optimize the use of testing, and to select testing efficiently,” Udelson said in a news release. “This tool is a good first step in helping clinicians quantify minimal risk when presented with a patient with stable chest pain, and opens up a conversation between doctor and patient on whether a test may be worthwhile.”