Diagnostic test shows potential to noninvasively identify significant coronary artery disease

Among patients with suspected or known coronary artery disease, use of a method that applies computational fluid dynamics to derive certain data from computed tomographic (CT) angiography demonstrated improved diagnostic accuracy vs. CT angiography alone for the diagnosis of ischemia, according to a study being published online by JAMA. The study is being released early to coincide with its presentation at the European Society of Cardiology Congress.

"Coronary computed tomographic angiography is a noninvasive anatomic test for diagnosis of coronary stenosis [narrowing of a blood vessel] that does not determine whether a stenosis causes ischemia [inadequate blood supply]. In contrast, fractional flow reserve (FFR) is a physiologic measure of coronary stenosis expressing the amount of coronary flow still attainable despite the presence of a stenosis, but it requires an invasive procedure. Noninvasive FFR computed from CT (FFRCT) is a novel method for determining the physiologic significance of coronary artery disease (CAD), but its ability to identify ischemia has not been adequately examined to date," according to background information in the article.

James K. Min, M.D., of the Cedars-Sinai Heart Institute, Los Angeles, and colleagues conducted a study to evaluate the performance of noninvasive FFRCT compared with an invasive FFR reference standard for diagnosis of ischemia. The study included 252 patients with suspected or known CAD from 17 centers in 5 countries who underwent CT, invasive coronary angiography (ICA), FFR, and FFRCT between October 2010 and October 2011. About 77 percent of patients had experienced angina within the last month. Ischemia was defined by certain criteria. Anatomically obstructive CAD was defined by a stenosis of 50 percent or larger on CT and ICA. Among 615 study vessels, 271 had less than 30 percent stenosis and 101 had at least 90 percent stenosis.

Among study participants, 137 (54.4 percent) had an abnormal FFR as determined by ICA. The researchers found that the diagnostic accuracy for FFRCT plus CT was 73 percent, which did not meet a prespecified primary end point for accuracy (as pre-specified based on the lower limit of a calculated 95 percent confidence interval). By comparison, diagnostic accuracy of CT alone for detecting coronary lesions with stenosis of 50 percent or greater, was 64 percent. When comparing FFRCT alone with CT alone for detecting these lesions, FFRCT demonstrated superior discrimination.

Coronary heart disease (CHD), also called coronary artery disease, is a condition in which plaque (plak) builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart muscle.

Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. When plaque builds up in the arteries, the condition is called atherosclerosis (ATH-er-o-skler-O-sis). The buildup of plaque occurs over many years.

Over time, plaque hardens and narrows your coronary arteries. This limits the flow of oxygen-rich blood to your heart muscle.