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SAN FRANCISCO, CA – October 30, 2013 – Clinical trial results demonstrate that a non-invasive CTA-based test accurately assesses coronary artery disease with results closely matching those of invasively measured FFR, and may inform potential revascularization treatment options, including angioplasty and coronary artery bypass surgery (CABG), better than currently used methods.  The findings of the HeartFlowNXT trial were presented today at the 25th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium. Sponsored by the Cardiovascular Research Foundation (CRF), TCT is the world’s premier educational meeting specializing in interventional cardiovascular medicine.

Clinical trial results demonstrate that a non-invasive CTA-based test accurately assesses coronary artery disease with results closely matching those of invasively measured FFR, and may inform potential revascularization treatment options, including angioplasty and coronary artery bypass surgery (CABG), better than currently used methods. The findings of the HeartFlowNXT trial were presented today at the 25th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium. Sponsored by the Cardiovascular Research Foundation (CRF), TCT is the world’s premier educational meeting specializing in interventional cardiovascular medicine.

Current guidelines for the management of stable coronary artery disease (CAD) recommend non-invasive ischemia testing such as treadmill testing, single photon emission computed tomography (SPECT), stress echocardiography, or cardiac magnetic resonance before invasive coronary angiography (ICA) or coronary revascularization is considered. An invasive test, fractional flow reserve (FFR), is considered the gold standard for lesion-specific coronary revascularization decisions in patients with stable CAD. 

However, the current non-invasive testing options such as treadmill testing, SPECT and stress echocardiography, correlate poorly to FFR, and thus selection of patients for invasive angiography and coronary revascularization is often inaccurate.

The HeartFlowNXT trial was a blinded, prospective core lab adjudicated trial that investigated FFRCT, a new non-invasive FFR calculation derived from coronary computed tomography angiography (CTA) images and using high-performance computing to create a three-dimensional map of the coronary arteries showing locations of obstructions and FFRCT values. FFR measures the ratio of maximal blood flow in a stenotic artery compared to normal blood flow.

The primary study objective was to compare per patient diagnostic performance of FFRCT compared to coronary CTA alone for the diagnosis of at least one hemodynamically significant stenosis, using direct measurement of FFR (?0.80) as the reference standard. The trial also measured per-vessel and per-patient diagnostic accuracy, sensitivity and specificity, as well as positive and negative predictive values of FFRCT.

The prospective study enrolled 254 patients scheduled to undergo non-emergent clinically indicated invasive angiography due to suspected coronary artery disease. 

The FFRCT data matched closely with invasively measured FFR. The area under the receiver operating characteristic curve (AUC) for FFRCT (?0.80) was 0.82 versus 0.63 for coronary CTA (lumen reduction ?50 percent) (p<0.0001) with invasive FFR as the reference standard. Per-patient sensitivity and specificity were 86 percent and 79 percent for FFRCT versus 94 percent and 34 percent for coronary CTA, and 91 percent and 51 percent for invasive coronary angiography (lumen reduction >50 percent).      

“Fractional flow reserve non-invasively calculated from coronary CTA data sets matches closely with invasively measured FFR and allows for identification of patients with hemodynamically significant coronary lesions with good accuracy. When compared to both coronary CTA and ICA, FFRCT led to a significant reduction in the proportion of false-positive results,” said lead investigator Bjarne L. Nørgaard, MD, PhD, from Aarhaus University Hospital in Denmark. 

“The addition of FFRCT to coronary CTA allows for a comprehensive anatomic and functional assessment of coronary artery disease.”

The HeartFlowNXT trial was funded by HeartFlow, Inc. Dr. Nørgaard reported no relevant disclosures.