Fractional Flow Reserve Plus Computed Tomography Reduced Invasive Angiography

Fractional flow reserve technology (FFR) combined with computed tomographic angiography (CTA) can provide noninvasive blood flow measurements in patients with chest pain and reduce the need for invasive coronary angiography, according to researchers at the European Society of Cardiology 2015 Congress.

This technology combines the measure of blood flow and pressure in the coronary artery from FFR with CTA. The combined technology (FFRCT) produces three-dimensional images to confirm blood flow measurements and intra-arterial pressure, which are then analyzed with a super computer.

In the PLATFORM trial (Prospective Longitudinal Trial of FFRCT Outcome and Resource Impacts), Pamela Douglas, MD, Duke University School of Medicine, and colleagues compared FFRCT as a diagnostic tool for blood flow measurements against conventional diagnostic strategies.

Previous studies, including the PROMISE and SCOT-HEART trials, compared anatomic and functional strategies and found that CTA improved the process of care, but that it increased invasive catheterization and revascularization rates without offering a significant reduction in the number of cardiovascular events.

“This approach significantly reduced the need for unnecessary invasive coronary angiography (ICA) which, although it is the gold standard for investigating chest pain, comes with the risk and costs of an invasive procedure,” Dr. Douglas said during the presentation.

The purpose of the study was to determine whether the use of an FFRCT guided strategy could reduce the rate of invasive angiograms that show no obstructive coronary artery disease (CAD), without increasing the risk of cardiovascular incidents.

Although CTA can identify stenosis in the coronary arteries, it cannot quantify how much this actually obstructs the blood flow. Myocardial perfusion stress imaging and stress echocardiography also test the blood supply to heart tissue, but still cannot determine if there is a blockage.

“Many patients who have blockages that are not interfering with blood flow may end up undergoing ICAs that show no evidence of obstructive coronary artery disease and could have possibly been avoided,” stated Dr. Douglas.

The study included 584 patients (median age 60.9 years) with new onset angina from 11 test centers in Europe.  The researchers divided the patients into two groups: those who would require a non-invasive procedure like stress testing or conventional CTA (n=204) and those who would have proceeded straight to an ICA (n=380). Patients were then assigned to be evaluated using the FFRCT method (n=297) or conventional testing (n=287).

Seventy-three percent of the patients who had conventional testing went on to have an ICA and had no significant blockages, compared with the 12% in the patients who first had FFRCT testing, the researchers found. Additionally, 61% of patients from the FFRCT group cancelled their ICA based on the FFRCT results.

The FFRCT reduced the number of ICAs that found no significant disease, but there was no difference in the rate of revascularization procedures between the 2 groups.

“The study shows that CTA plus FFRCT more effectively triages patients for invasive procedures than usual care strategies,” Dr. Douglas concluded. “Although FFRCT is a relatively new technique, PLATFORM demonstrates that it is feasible and safe with high utility in busy clinical settings.”

Disclosures: The study was supported by HeartFlow, Inc., Redwood City, CA, which makes the FFRCT software. Dr. Douglas and other co-authors received grants for the study from Heartflow.

Reference

1. Douglas P, Pontone G, Hlatky MA, Patel MR et al. #5995. Prospective Longitudinal Trial of FFRCT Outcome and Resource Impacts. Presented at: ESC Congress; Aug 29-Sept 2, 2015; London, United Kingdom.