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Blood test for patients with CAD symptoms may reduce unnecessary cardiac referrals
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Patients with symptoms of obstructive CAD with a low score using a blood-based age/sex/gene expression test were less likely to be referred to a cardiologist, have positive findings and have an adverse CV event after 1 year, according to a study in The American Journal of Medicine.
“These findings show that a simple blood test can distinguish people who are likely to have obstructive coronary disease from those who are not, thereby helping us better target therapy and reduce unnecessary cardiac testing,” Joseph A. Ladapo, MD, PhD, assistant professor of general internal medicine at UCLA David Geffen School of Medicine, told Cardiology Today.
Blood test for CAD
The age/sex/gene expression score (ASGES) is used to determine the probability of obstructive CAD through a blood test (Corus CAD, CardioDx Inc.), which takes into consideration a gene expression profile and the patient’s sex and age. The score ranges from 1 to 40, and higher scores indicate a higher probability of obstructive CAD and adverse events. A low ASGES, defined as equal to or less than 15, has previously been proved to have a 96% negative predictive value.
“Physicians see many patients with chest pain, shortness of breath, and other signs and symptoms suggestive of obstructive coronary disease,” Ladapo said in an interview with Cardiology Today. “The ASGES blood test can be used by clinicians to identify a safe and effective course of care for these patients, all without exposing many of them to the risks of radiation and contrast dye associated with other cardiac tests, and also reducing the burden of taking time away from work to undergo testing.”
Researchers utilized ASGES on 566 patients (median age, 56 years; 51% women) who reported symptoms related to obstructive CAD to their primary care physician from August 2012 to August 2014. Patients were stable and did not have diabetes or a history of CAD. Average BMI was 30 kg/m2, and 18% of patients reported smoking in the past 30 days. The cohort included patients with hypertension (46%) and dyslipidemia (53%).
The primary outcome was to analyze whether ASGES can be included in the decision-making process for cardiac referrals, which were defined as referral for further cardiac testing or a cardiologist. Major adverse effects, including MI, stroke, revascularization procedures and cardiac-related death, were reviewed at 1-year follow-up.
Study results
Patients with low (n = 252) and elevated ASGES (n = 314) had statistically significant differences in cardiac referral rates. Ten percent of patients with low scores were referred vs. 44% of patients with elevated scores (OR = 0.15; P < .001). After an adjustment for BMI, sex, age, hypertension, smoking status and dyslipidemia, the link between those with low ASGES and referral rates remained low (OR = 0.18; P < .0001).
Follow-up test results were available for 84 patients. Ten patients with elevated ASGES and no patients with low ASGES had a positive invasive coronary angiography or cardiac stress test for obstructive CAD.
At follow-up, 1.2% of patients with low ASGES and 4.5% of patients with elevated ASGES experienced major adverse cardiac events and coronary artery revascularizations (P = .03).
“Our work provides evidence supporting the value of using precision medicine in the delivery of [CV] care,” Ladapo said to Cardiology Today. “Personalizing medicine will help us better care for our patients and improve their health outcomes. We need more research in this area.” – by Darlene Dobkowski
Disclosure: The study was funded by CardioDx Inc. Ladapo reports receiving an honorarium and research support from CardioDx Inc. Please see the full study for the other researchers’ relevant financial disclosures.
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