John A McPherson, associate professor of Medicine, Vanderbilt University School of Medicine, USA, presented results of the IMPACT trial at the ACC 2013 sessions. The data showed how the Corus CAD (CardioDx), a blood-based gene expression test, influenced cardiologists’ patient management decisions in women with suspected obstructive coronary artery disease.
Following the use of the Corus CAD test, in the IMPACT (Investigation of a molecular personalized coronary gene expression test on cardiology practice pattern) trial, a change in diagnostic testing (eg, an increase or decrease in the use of myocardial perfusion imaging, computed tomography angiography and/or cardiac catheterisation) was noted in 60% of female patients (p<0.001). Among the patients whose management changed, 91% had decreased testing. Among the female patients with decreased testing, 94% had low (≤15) Corus CAD scores. At six-month follow-up, no adverse cardiovascular events were observed.
“Personalised medicine is becoming an increasingly valuable diagnostic tool to aid clinician decision-making,” said McPherson. “The IMPACT trial showed that there is significant potential for personalised medicine to be integrated into real-world clinical practice as more than an aid, but a guide for clinicians to more accurately identify which patients need further diagnostic evaluation, helping many patients avoid unnecessary invasive testing or exposure to imaging agent intolerance and related risks to radiation exposure.”
The investigators evaluated data from 57 stable female patients presenting with atypical, typical and non-cardiac chest pain and related symptoms without a history of coronary artery disease who were referred to cardiologists at Vanderbilt University Medical Center. The cardiologists’ patient management decisions were assessed before and after the Corus CAD score was known for each patient. Corus CAD measured the peripheral blood cell expression levels of 23 genes to determine the likelihood of obstructive coronary artery disease.
CardioDx recently announced the publication of the COMPASS (Coronary obstruction detection by molecular personalized gene expression) study in Circulation: Cardiovascular Genetics. Results of the prospective, multicentre US study showed that Corus CAD outperformed traditional stress testing with myocardial perfusion imaging, demonstrating high accuracy with both a higher sensitivity (89% vs 27%, p<0.001) and higher negative predictive value (96% vs 88%, p<0.001) than myocardial perfusion imaging for assessing obstructive coronary artery disease. Moreover, the presence of breast tissue and fatty tissue may produce false-positive test results when using myocardial perfusion imaging in women. Side effects such as radiation exposure and contrast agent allergies resulting from myocardial perfusion imaging can be harmful for women. The use of myocardial perfusion imaging increases with age, and radiation exposure during one test is equivalent to 39 mammograms.
“All tests are not created equal and women need to be their own health advocates as current methods for evaluating coronary artery disease do not account for the critical biological differences in men and women,” said Alexandra Lansky, associate professor of Medicine and director of the Cardiovascular Research Center at Yale University School of Medicine.
“Diagnosing heart disease in women is historically more difficult as they may present with symptoms that are more varied, non-specific and atypical compared to those presented by men. Traditional stress tests for obstructive coronary artery disease are also not as sensitive in women, which adversely affects the accuracy of test results. Using Corus CAD earlier in the screening process may optimise diagnostic performance and help to reduce unnecessary health care expenditures related to diagnostics.”
About the Corus CAD test
The Corus CAD test is intended for use in non-diabetic stable patients who present with typical or atypical symptoms suggestive of coronary artery disease, with no known history of CAD, no prior myocardial infarction or revascularisation procedure, and who are not currently taking steroids, immunosuppressive agents or chemotherapeutic agents.