Past Event: Oden Institute Seminar

Noninvasive Functional Assessment of Coronary Artery Disease Using CT and Computational Fluid Dynamics

Charles Taylor, Founder and Chief Technology Officer, HeartFlow, Inc.

Abstract

Heart disease resulting from atherosclerosis in the coronary arteries is the cause of nearly one-third of all global deaths. The severity of coronary artery disease and the consequent effect on blood flow to the heart are difficult to measure, yet this information is critical for treating patients. Currently, the gold-standard for assessing the functional significance of coronary artery disease, fractional flow reserve (FFR) involves invasive measurement of pressure in the coronary arteries at the time of diagnostic cardiac catheterization. FFRCT is a noninvasive technology whereby patient-specific models of blood flow are constructed from coronary CT angiography (cCTA) data and used to provide data to physicians related to the functional significance of coronary artery disease. HeartFlow employs a service model to provide FFRCT results to ordering physicians whereby patient data is uploaded through a secure web browser, processed on-site using custom software and high performance computing platforms and transmitted back to the physician through a secure web browser. FFRCT requires an accurate segmentation of the coronary artery lumen from cCTA data, but additionally, it leverages established biologic principles relating form (anatomy) to function (physiology). Finally, FFRCT exploits recent advances in computational fluid dynamics to solve the governing equations of blood flowing in the coronary arteries. Ultimately, any theoretical model must be tested against experiment and the data must be the final arbiter of model validity. FFRCT has been evaluated against measured FFR data in three diagnostic accuracy trials to date. Most recently, the NXT trial has demonstrated accuracy against measured FFR data in 254 patients and 484 vessels not only significantly exceeding that of cCTA alone, but superior to that reported for any other noninvasive diagnostic test when compared to measured FFR as the reference standard. In a demonstration of the expected clinical use of the technology, FFRCT correctly reclassified 68% of coronary CTA false positive patients as true negatives. The clinical use of this technology could substantially improve the identification of patients that would benefit from coronary stenting and hence should be referred to invasive cardiac catheterization. Clinical trials examining the impact of FFRCT on clinical outcomes and costs are underway. In addition, at present, FFRCT is being used for clinical decision making in parts of Europe and Asia and FDA Clearance is pending in the U.S. Ultimately, tens of millions of patients worldwide could benefit from this technology. This talk will describe the clinical need, scientific basis, numerical methods and clinical validation of HeartFlow’s FFRCT technology.