Feature | November 01, 2013

Study Demonstrates Accuracy of Noninvasive CT-FFR in Evaluating CAD Patients

CT FFR, HeartFlow

HeartFlow's CT-FFR software uses supercomputing algorithms to calculate the flow of blood through a lesion in part by tracking the speed of the CT iodine contrast.

CT FFR, HeartFlow

HeartFlow's CT-FFR software showing a coronary artery tree created from a CT scan showing the FFR for a lesion.

November 1, 2013 — Clinical trial results demonstrated that a noninvasive coronary computed tomography angiography (CTA)-based test accurately assesses coronary artery disease (CAD) with results closely matching those of invasively measured fractional flow reserve (FFR), and may inform potential revascularization treatment options, including angioplasty and coronary artery bypass surgery (CABG), better than current methods. The findings of the HeartFlowNXT trial were presented at the 25th annual Transcatheter Cardiovascular Therapeutics scientific symposium (TCT 2013).
 
Current guidelines for the management of stable 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, FFR, is considered the gold standard for lesion-specific coronary revascularization decisions in patients with stable CAD. 
 
However, the current noninvasive 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 FFR-CT, a new, noninvasive FFR calculation derived from CTA images and using high-performance computing to create a 3-D map of the coronary arteries showing locations of obstructions and FFR-CT values.
 
The primary study objective was to compare per-patient diagnostic performance of FFR-CT compared to coronary CTA alone for the diagnosis of at least one hemodynamically significant stenosis using direct measurement of FFR (? 0.8) 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 FFR-CT.
 
The prospective study enrolled 254 patients scheduled to undergo non-emergent clinically indicated invasive angiography due to suspected CAD. 
 
The FFR-CT data matched closely with invasively measured FFR. The area under the receiver operating characteristic curve (AUC) for FFR-CT (? 0.8) was 0.82 versus 0.63 for coronary CTA (p < 0.0001) with invasive FFR as the reference standard. Per-patient sensitivity and specificity were 86 percent and 79 percent for FFR-CT 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, FFR-CT led to a significant reduction in the proportion of false-positive results,” said Bjarne Nørgaard, M.D., Ph.D., Aarhaus University Hospital, Denmark and lead investigator of the study. “The addition of FFR-CT to coronary CTA allows for a comprehensive anatomic and functional assessment of coronary artery disease.”
 

Limits of the Current Technology

CT-FFR may one day eliminate the need to refer patients for diagnostic catheter angiographies. However, today, users of the HeartFlow technology say it requires sending the CT DICOM dataset to the company in California. It then takes the supercomputing power of the HeartFlow computer system about a day to process the data and render a report. While this may eliminate CT-FFR's use for acute chest pain patients, it offers an option for patients considering elective PCI. Coronary CT experts say computing speed and power doubles every couple years, which will eventually enable CT-FFR to be processed onsite in minutes, instead of days or hours. 

For more information: www.crf.org

Related Content

Webinar | November 17, 2017
The CME webinar “Innovation and Success in 3D-inspired Development of the Business and Clinical Practice,” will take
News | Antiplatelet and Anticoagulation Therapies| November 16, 2017
Bristol-Myers Squibb Company and Pfizer Inc. released real-world data (RWD) of outcomes associated with direct oral...
SPRINT Trial Data Support New AHA/ACC Hypertension Guidelines
News | Hypertension| November 16, 2017
Findings from a landmark study funded by the National Institutes of Health (NIH) support a key component of the new...
Siemens Healthineers Announces First U.S. Installs of Somatom go.Up CT System
News | Computed Tomography (CT)| November 15, 2017
November 15, 2017 — Center for Diagnostic Imaging (CDI), one of the nation’s largest providers of diagnostic imaging
Videos | FFR Technologies| November 15, 2017
A discussion with William Fearon, M.D.
Philips Azurion Image-Guided Therapy Platform Improves Clinical Workflow for Interventional Procedures
News | Angiography| November 15, 2017
Philips announced the results of a comprehensive, independent, two-year study demonstrating the clinical workflow...
Videos | Heart Valve Technology| November 15, 2017
Ted Feldman, M.D., MSCAI FACC FESC, director of the cardiac cath lab, Evanston Hospital, is the principal investigato
Videos | Left Atrial Appendage (LAA) Occluders| November 14, 2017
Vivek Reddy, M.D., director of cardiac arrhythmia services and professor of medicine, cardiology, Mount Sinai Hospita
Mexican Doctors Safely Reuse Donated Pacemakers After Sterilization
News | Pacemakers| November 10, 2017
Mexican doctors have safely reused donated pacemakers after sterilization, shows a study presented at the 30th Mexican...
Siemens Healthineers Introduces Share360 Tailored Service Portfolio
News | Cardiac Imaging| November 10, 2017
To address the specific needs of medical imaging clinical engineering departments nationwide, Siemens Healthineers has...
Overlay Init