Gene expression testing provides valuable tissue and cell-specific information about the molecular mechanisms involved in disease processes, enabling evaluation of an individual patient's disease state, activity, and/or progression at a given point in time.

At the University of California, Irvine's School of Medicine (Irvine, CA, USA) scientists enrolled 537 stable patients with symptoms suggestive of coronary artery disease who had been referred to myocardial perfusion imaging (MPI) at 19 USA sites. A blood sample was obtained in all patients prior to MPI, and gene expression testing was then performed, with study investigators blinded to gene expression-test results. A total of 431 patients were eligible for analysis, having completed gene expression testing, MPI and either invasive angiography or computed tomography angiography (CTA).

The gene expression test was superior to MPI in diagnostic accuracy, with the sensitivity for the former at 89%, while for MPI it was only 27%. The negative predictive value was 96% for the blood test and 88% for MPI, which was a statistically significant difference. The gene expression test demonstrated excellent performance for ruling out obstructive coronary artery disease relative to both invasive angiography and CTA.

The gene expression test used in the study, called Corus CAD (CardioDx; Palo Alto, CA, USA), measures the RNA levels of 23 genes from a whole blood sample. Because these RNA levels are increased or decreased when obstructive coronary artery disease is present, the Corus CAD score indicates the likelihood that an individual patient does not have obstructive coronary artery disease.

Mark Monane, MD, chief medical officer of CardioDx, said "Corus CAD has now been validated in more than 1,100 patients in three separate studies. For physicians, methods to improve the diagnosis of symptoms suggestive of coronary artery disease represent a huge unmet need, and the Corus CAD test may help clinicians make better decisions. For patients, the test may lead to better diagnostic accuracy as well as avoidance of unnecessary procedures. For payers, we believe that Corus CAD can address a major expense category." The study results were presented at the American Heart Association Scientific Sessions conference held November 11-16, 2011, in Orlando (FL, USA).

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University of California, Irvine's School of Medicine
CardioDx