CCTA: Shedding light on appropriateness of repeat scans

Guidelines offer some direction on the appropriate use of repeated coronary CT angiography (CCTA), but how often is it actually catching anything of significance? Published July 18 in Circulation: Cardiovascular Imaging, this was the question posed by researchers hoping to guide future use.

The research team led by Kanako K. Kumamaru MD, PhD, of Boston’s Brigham and Women’s Hospital, working with colleagues at the Takase Clinic in Takasaki, Japan, reviewed 555 repeat CCTAs representing 492 patients. They looked for patterns between incidents of stenosis and worsening coronary artery disease in the patient population undergoing imaging. These repeat CCTAs were considered to be appropriate per 2010 guidelines. Scans occurred between February 2006 and April 2013.

A limited number of patients had more repeat studies: one patient received four repeat scans, six patients received three repeat scans, and 48 patients received two repeat scans. The remainder received only one repeat scan. The mean time between scans was 34.2 months.

Significant stenosis was discovered in 12.3 percent of the repeat scans; 5.9 percent were considered to be indeterminate. Subsequent catheter angiography performed on portions those patients who were determined to have stenosis and those whose cases were indeterminate detected significant stenosis in more than two-thirds of patients. Altogether, significant stenosis was found in 13.3 percent of patients.

The researchers determined that the probability of patients having significant stenosis was 4.5 percent in patients who were not diabetic, had more than three years between scans, and had at less than 26 percent stenosis on prior CCTA images. Significant stenosis was detected in 17.1 percent of patients who had at least one of the three previously mentioned factors. In patients with no detectable stenosis in the initial scan, only 1.8 percent developed significant stenosis.

This research was performed in Japan on an ethnically homogenous group, which may have some bearing on the results. However, as Japan also boasts three times more scanners per million individuals than in the U.S., the research team was better able to obtain a large study size.

Ultimately, Kumamaru et al could not determine precisely which patients would best be served by repeat scans. They suggested that apart from clinician suspicion of need for repeat determinations, diabetes, longer time between scans and higher levels of stenosis on the initial scan may indicate a need to reassess the patient through CCTA.