FFR-derived CT tops CCTA for predicting cardiac disease outcomes

Fractional flow reserve derived from CT (FFR-CT) is a superior predictor of long-term outcomes of heart disease compared to traditional coronary CT angiography (CCTA), according to a new study published in Radiology.

Results of the prospective trial—Analysis of Coronary Blood Flow Using CT Angiography: Next Steps (NXT)—found a positive FFR-CT exam (a score of 0.8 or less) was a better predictor of outcomes such as myocardial infarction, death and other major adverse cardiac events compared to a positive CCTA exam.

“Coronary CT angiography is a well-established diagnostic modality that provides anatomic assessment of stenosis severity with an excellent negative predictive value but is limited by poor specificity for detecting lesion-specific ischemia,” explained Abdul Ihdayhid, MBBS, with Monash University in Australia, and colleagues.

He went on to state that other trials have shown FFR-CT’s capability for producing measurements similar to that of conventional fractional flow reserve for identifying ischemia, but FFR-CT’s long-term prediction capabilities compared to CCTA’s are not widely understood.

Ihdayhid et al. analyzed the data of 206 participants from the NXZT trial who had suspected stable coronary artery disease. All were referred for invasive angiography and underwent fractional flow reserve, CCTA and FFR-CT.

After a median 4.7 year follow-up, the team observed that a positive FFR-CT study could more accurately predict myocardial infarction (MI), death, revascularization procedures and major adverse cardiac events compared to a positive CCTA exams (stenosis of 50% or greater in at least one artery).

Broken down, FFR-CT achieved an area under the curve (AUC) of 0.71 for predicting MI, death and revascularization compared to 0.52 for CCTA. For predicting major adverse cardiac events, FFR-CT achieved an AUC of 0.76 compared to 0.54 for CCTA. There were no cardiac deaths or myocardial infarctions in those with a normal FFR-CT exam.

Looking further down the line, FFR-CT could become a first-line method for assessing patients with suspected coronary artery disease that will require intervention, wrote Carole Dennie and Fraser D. Rubens, both with the University of Ottawa in Canada, in an accompanying editorial. However, five hour turnaround times, low reimbursement rates and a lack of commercially available FFR-CT applications remain challenges the technique will have to overcome.

“The path forward is exciting as this opens the door for discussions on how to redefine the indications and strategies that will form the basis of tomorrow’s guidelines on the treatment of coronary disease,” the pair wrote. “In this case, we can give thanks to data parsing as it helps us on our voyage and fills the tank with optimism of the questions we can now ask.”