Image source: GE Healthcare

In a real-world, clinical setting, the negative predictive value of coronary CT angiography (CCTA) in low-risk patients is very high and "exceptionally helpful" in predicting freedom from events for up to three years, according to a study in the Aug. 15 issue of the American Journal of Cardiology .

Poorya Fazel, MD, from Baylor University Medical Center in Dallas, and colleagues said 64-slice CCTA is being used more often in the evaluation of patients with chest pain. The strength of this test is its high specificity and negative predictive value to exclude coronary artery disease (CAD). However, its use remains controversial because of the “theoretical risks of radiation, additional costs of the test, and no long-term data to suggest that excluding CAD by use of this test results in positive patient outcomes."

The researchers enrolled 436 patients who underwent 64-slice CCTA because of chest pain thought to be anginal. "[P]atients presented with chest pain concerning for angina, but it was thought that initial referral for invasive evaluation was unnecessary," the authors wrote. "Individually, these patients were considered by their referring physician to be at lower risk for significant, flow-limiting CAD based on their age, lack of risk factors or quality of their chest pain."

Also, the investigators reported that a smaller subset of patients initially underwent stress testing, but had equivocal findings or continued symptoms that warranted further evaluation.

Of the total patient cohort, 376 had “no significant CAD” on the basis of CCTA results. Of the 60 patients who were believed, according to CCTA results, to have “flow-limiting” CAD, 57 percent ended up having percutaneous coronary intervention or coronary artery bypass grafting, according to Fazel and colleagues. The remaining 43 percent did not have true flow-limiting disease on coronary catheterization and were treated medically.

In a follow-up of the patients after 36 months, the researchers found that 100 percent of those patients with minimal or no disease by CCTA were free of events or intervention.

“By avoiding further invasive treatments, there is a significant potential cost savings in patients who are sent for noninvasive coronary angiography rather than invasive angiography,” the authors concluded.