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The Clinical Utility of Gene Expression Testing on the Diagnostic Evaluation of Patients Presenting to the Cardiologist With Symptoms of Suspected Obstructive Coronary Artery Disease: Results From the IMPACT (Investigation of a Molecular Personalized Coronary Gene Expression Test on Cardiology Practice Pattern) Trial

McPherson, John A. MD*; Davis, Kelly MD; Yau, May MS; Beineke, Phil BS; Rosenberg, Steven PhD; Monane, Mark MD; Fredi, Joseph L. MD*

Critical Pathways in Cardiology: June 2013 - Volume 12 - Issue 2 - p 37–42
doi: 10.1097/HPC.0b013e3182822bd0
Original Article

Accurate, noninvasive evaluation for obstructive coronary artery disease (CAD) remains challenging and inefficient. In this study, 171 patients presenting with stable chest pain and related symptoms without a history of CAD were referred to 6 cardiologists for evaluation. In the prospective cohort of 88 patients, the cardiologist’s diagnostic strategy was evaluated before and after gene expression score (GES) testing. The GES is a validated, quantitative blood-based diagnostic test measuring peripheral blood cell expression levels of 23 genes to determine the likelihood of obstructive CAD (at least 1 vessel with ≥50% angiographic coronary artery stenosis). The objective of the study was to measure the effect of the GES on diagnostic testing using a pre/post study design. There were 83 prospective patients evaluable for study analysis, which included 57 (69%) women, mean age 53 ± 11 years, and mean GES 12.5 ± 9. Presenting symptoms were classified as typical angina, atypical angina, and noncardiac chest pain in 33%, 60%, and 7% of patients (n = 27, 50, and 6), respectively. After GES, changes in diagnostic testing occurred in 58% of patients (n = 48, P < 0.001). Of note, 91% (29/32) of patients with decreased testing had low GES (≤15), whereas 100% (16/16) of patients with increased testing had elevated GES (P < 0.001). A historical cohort of 83 patients, matched to the prospective cohort by clinical factors, had higher diagnostic test use compared with the post-GES prospective cohort (P < 0.001). In summary, the GES showed clinical utility in the evaluation of patients with suspected obstructive CAD presenting to the cardiologist’s office.

From the *Vanderbilt University, MCE, South Tower, Nashville, TN; and CardioDx, Inc., Faber Place, Palo Alto, CA.

Accepted for publication December 8, 2012.

The trial registration numbers was NCT01251302.

This work was presented, in part, at the Quality of Care and Outcomes Research in Cardiovascular Disease and Stroke 2012 Scientific Sessions, May 9–11, 2012, Atlanta, GA. Research support for this work was provided by CardioDx, Inc.

Funding was provided by CardioDx, Inc.

Dr. McPherson receives research support from CardioDx, Inc. Ms. Yau, Mr. Beineke, Dr. Rosenberg, and Dr. Monane are employees of CardioDx, Inc. All other authors have no potential conflicts of interest to disclose.

Reprints: John A. McPherson, MD, 1215 21st Avenue South, MCE, Suite 5209, Nashville, TN 37232. E-mail:

© 2013 by Lippincott Williams & Wilkins