Blood Test Plus Clinical Characteristics May Improve CAD Diagnosis

Asimple blood test can accurately, noninvasively, and quickly diagnose heart disease, according to a study published in the Journal of the American College of Cardiology. The soon-to-be commercialized test uses clinical and multi-protein blood test to predict the presence of anatomically significant coronary artery disease (CAD).

CAD is the most common form of heart disease, killing more than 370,000 people in the United States annually, according to the American Heart Association. The current diagnostic methods—CT angiography and stress testing—have drawbacks, including the need for ionizing radiation and high cost.

"CAD is a public health concern, and an efficient manner for its noninvasive detection could potentially result in reduction of morbidity, mortality, and cost of this disease," writes lead author Nasrien Ibrahim, M.D., from Massachusetts General Hospital (Boston).

The researchers used data from 1,251 patients enrolled in the CASABLANCA (Catheter Sampled Blood Archive in Cardiovascular Diseases) study who were referred for coronary angiography (2008 through 2011). A panel of 109 biomarkers was evaluated from blood samples collected immediately before and after the angiographic procedure using the Luminex xMAP multiplex technology platform (Luminex Corporation; Austin, Texas). Candidate proteins and clinical features were selected using least angle regression, in which factors are selected one at a time and evaluated for predictive performance and goodness of fit. Variables are added if they improve the score.

In the training cohort, independent predictors of CAD (70 percent or more) in any one vessel included clinical variables (male sex and previous percutaneous coronary intervention) and four biomarkers (midkine, adiponectin, apolipoprotein C-I [apo C-I], and kidney injury molecule–1 [KIM-1]), which the authors say represent "a unique pathophysiological mix." The combined score "strongly" predicted severe CAD in all subjects in the training cohort. Across scores, the CAD algorithm had 77 percent sensitivity, 84 percent specificity, 90 percent positive predictive value, and 67 percent negative predictive value for severe CAD at the optimal score cutpoint in the validation set. An elevated score also significantly predicted incident acute myocardial infarction during 3.6 years of follow up.

"Advantages of such a reliable clinical and biomarker score include the fact such a technology can be widely disseminated in a cost-effective manner, is easily interpreted, and might be associated with a well-defined sequence of therapeutic steps to reduce risk for CAD-related complications, such as antiplatelet or lipid-lowering therapy," writes Ibrahim.

The test is being commercialized as HART CAD by Prevencio (Kirkland, Wash.). The company says it takes two hours for results and is cheaper than the current diagnostic standards (CT angiogram $2,000 on average and a cardiac catheterization $47,000 on average). Prevencio says it plans to conduct trials for U.S. Food and Drug Administration approval in 2018 and hopes the test would be commercially available by 2019.

Several authors report financial ties to the diagnostic firm Prevencio (Kirkland, Wash.), which funded this study.

Takeaway: A blood test, in combination with clinical features, produces a score that can efficiently and effectively gauge risk of CAD. Such a test could improve diagnosis and early treatment, while decreasing health care costs and deaths.