Cardiovascular genomic's specialist Cardiodx Inc.'s test to detect obstructive coronary artery disease (CAD) received long-term validation from a study published in this month's American Heart Journal. The Corus CAD test was evaluated in a genomic sub study of the Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE), which was sponsored by the National Heart, Lung and Blood Institute.

PROMISE results come shortly after the Redwood City, Calif.-based company raised $18.1 million in equity financing from a total offering amount of $41.8 million, last month.

The 2,370-patient study showed that individuals with low Corus CAD test scores had a lower likelihood of obstructive CAD in the arteries and the opposite is true for higher scores. The private company launched Corus CAD on the market in 2009.

Mark Monane, Cardiodx's CMO, said PROMISE tested a larger population than both PREDICT and COMPASS, two validation trials that evaluated the Corus CAD test. Monane said PROMISE addresses provider concerns over seeing the test evaluated on a larger patient population.

"The study helped confirm and extend previous information that the test is valid and that it measures what we want it to measure, which is the likelihood of obstructive CAD," Monane, told Medical Device Daily. "The trial gave us independent confirmation [of Corus CAD] with a large patient size."

The primary analysis found that the clinical event rate was lower in patients with low Corus CAD test scores as compared to patients with higher Corus CAD test scores. Additionally, the clinical event rate for patients with low Corus CAD test scores compared to noninvasive cardiac testing was low and no different from a negative or normal cardiac stress test or CT-angiography at 25-month median follow-up.

Nearly half of the patients in the sub-study were randomized to the coronary CT-angiography arm. In this group, 10.1 percent of patients were found to have obstructive CAD.

The relationship between Corus CAD test scores and clinical event rates remained significant even after adjusting for common clinical risk factors using the Framingham Risk Score. When the Corus CAD test was added to functional or anatomical testing, the Corus CAD test score provided independent and incremental information beyond that of noninvasive diagnostic imaging and helped to accurately reclassify patients to their appropriate risk levels. The increased risk of clinical events seen with elevated Corus CAD test scores were largely driven by a higher rate of revascularization procedures in this group, thus reaffirming that the likelihood of obstructive CAD increased with higher Corus CAD test scores, the company said.

Monane said that right now there are a number of blood tests that help tell the clinician about the future risk of a heart attack or a major adverse cardiovascular outcome. However, Corus CAD is different because it "focuses on the current likelihood" of a patient having obstructive CAD.

Corus CAD has been developed to be used in the early diagnostic setting, or primary care – before patients get to a cardiologist. It relies on a score, which clinicians use, along with other clinical information, to determine whether further cardiac testing is necessary, which can help patients avoid unnecessary exposure to radiation associated with medical imaging testing, as well as possible reactions to imaging dyes and/or potential complications from invasive cardiac tests requiring catheterization. The Corus CAD test is sex-specific to account for cardiovascular differences between men and women.

"I want to be perfectly clear, our test is not meant to substitute for other tests, but our test is meant to be used early in the diagnostic process," Monane said. "For some patients, the test will be helpful to rule out a cardiac cause."