HeartFlow’s non-invasive fractional flow reserve technology failed to meet pre-determined rates of accuracy in a recent clinical trial, but researchers and clinicians remained optimistic that the new system may yet replace invasive testing for coronary artery disease.
In the DeFACTO study, which enrolled more than 250 patients, FFR based on computed tomography imaging beat invasive FFR in identifying lesions and produced higher per-patient sensitivity.
"These study results suggest the potential of FFR-CT as a promising noninvasive method for identification of individuals with ischemia," according to the study results. "The present study findings can be considered proof of concept of the feasibility of this novel technology and, to our knowledge, represent the 1st large-scale prospective demonstration of the use of computational models to calculate rest and hyperemic coronary pressure fields from typically acquired CT images."
Nevertheless, the study failed to produce the primary outcome, which was defined as diagnostic accuracy with a lower bound above 70%.
CT-based FFR produced accuracy of 73%, which beat the 64% accuracy of CT alone, but the lower bound for FFR-CT was just shy of the desired outcome at 67%, according to the study.
That may mean mixed results for study sponsor HeartFlow, developer of non-invasive FFR-CT technology which won the EuroPCR Innovation Award last year, based on findings from a clinical trial showing that it can help identify coronary lesions that are causing ischemia.
Fractional flow reserve is usually measured using a catheter and wire inserted through the thigh and into the heart’s blood vessels. The HeartFlow algorithm can use CTs generated non-invasively to calculate FFR. The aim is to help physicians to decide how best to treat the narrowed arteries – whether via medical therapy, stent or open-heart bypass surgery – based on the non-invasive imaging alone.
Despite missing the mark, some remained highly optimistic about the potential for FFR-CT technology to replace invasive FFR as a standard of care.
"The current report describes an important noninvasive technology that may improve existing care and has the potential to outperform established noninvasive technologies," Duke University’s Dr. Manesh Patel wrote in an editorial accompanying the study in the Journal of the American Medical Assn.
HeartFlow’s technology "represents a novel and important innovation, with the possibility not only to diagnose but also to help direct invasive treatment," Patel added.