PALO ALTO, Calif., March 25, 2013 /PRNewswire/ -- CardioDx, Inc., a pioneer in the field of cardiovascular genomic diagnostics, today announced data demonstrating that Corus® CAD, the only clinically validated gene expression test for the assessment of obstructive coronary artery disease (CAD), has higher diagnostic accuracy than commonly used risk assessment modalities including symptom evaluation and myocardial perfusion imaging (MPI) in women. The sex-specific analysis of the PREDICT ( Personalized Risk Evaluation and Diagnosis in the Coronary Tree) Trial was presented during a poster session at the Women's Health 2013: 21 st Annual Congress, which took place in Washington D.C. from March 22 nd - 24 th.
There is a growing body of clinical evidence confirming that standard diagnostic approaches used to evaluate patients for obstructive CAD lead to many unnecessary noninvasive and invasive procedures such as MPI, stress echocardiogram, computed tomography angiography and coronary angiography, especially in women . According to the results of the PREDICT Trial, MPI was not a significant predictor of obstructive CAD in women. This may be due to the presence of breast and fatty tissue in women, which leads to a higher rate of false-positive diagnoses  and, consequently, a higher rate of unnecessary referrals for additional invasive testing. The study also found that chest pain and other clinical factors are not reliable predictors of obstructive CAD in women. The traditional chest pain symptom classification as defined by Diamond and Forrester is helpful in diagnosing men, but does not correspond to presence of obstructive CAD in women. Furthermore, women with obstructive CAD tend to present with atypical, nonspecific symptoms such as shortness of breath, fatigue, and abdominal pain. Only the Corus CAD score and dyslipidemia were associated with the findings of obstructive CAD in women.
"Since the symptoms of coronary disease in women are not as well defined as in men, clinicians cannot use the same assessment criteria in women as they do in men," said Alexandra Lansky, MD, Associate Professor of Medicine and Director of the Cardiovascular Research Center, Yale University School of Medicine, the senior author of the study and one of the PREDICT co-investigators. "Women have more angina and less obstructive coronary artery disease compared to age-matched men and are significantly over-referred to invasive coronary angiography, as current noninvasive diagnostic approaches have limitations in women. Women need tests that are both specific to their biology and can reliably assess the origin of their symptoms. Corus CAD is the only sex-specific test for evaluating obstructive CAD and represents a paradigm shift in how clinicians may diagnose heart disease in women, who account for half of the U.S. population."The PREDICT cohorts analyzed included 1,160 stable non-diabetic men and women referred for cardiac catheterization with typical and atypical symptoms suggestive of obstructive CAD or who were asymptomatic with a high risk of CAD: a substudy of 492 women was included in this sex-specific analysis. Of the women referred to invasive coronary angiography with abnormal MPI results (N=295), only 22 percent had obstructive CAD upon invasive coronary angiography. The study showed that Corus CAD results were more accurate than MPI and were significantly associated with the extent and severity of obstructive CAD. Corus CAD was a significant classifier of obstructive CAD in the overall population (p<0.001) and in the male (p=0.001) and female (p<0.001) subgroups separately, whereas MPI was not found to be an independent indicator of obstructive CAD. Each 10-point increase in the Corus CAD score was associated with a twofold increase in the likelihood of obstructive CAD in men, and a 3.4-fold increase in the likelihood of obstructive CAD in women. The results demonstrate the improved ability of Corus CAD to safely exclude obstructive CAD as a diagnosis, particularly in women.