The report is a product of the VA/HSR Evidence Synthesis Program.

Evidence Brief: Coronary Computed Tomography Angiography with Fractional Flow Reserve in Non-invasive Diagnosis of Coronary Artery Disease

Non-invasive diagnostic strategies for evaluating patients with stable chest pain include functional imaging and anatomic imaging with coronary computed tomography angiography (CCTA). CCTA has good diagnostic accuracy for identifying obstructive coronary artery disease (CAD), but it cannot assess the functional significance of coronary artery narrowing. Fractional flow reserve (FFR) measured invasively is considered the gold standard for detecting functionally significant CAD. HeartFlow uses computer modeling to non-invasively estimate FFR from CCTA images. In 2019, VA/HSR&D’s Evidence Synthesis Program (ESP) synthesized the evidence on the use of HeartFlow for the diagnosis of CAD and identified important gaps in the evidence. The review found that in community settings, HeartFlow FFR_CT analysis reduced the use of invasive coronary angiography (ICA) among patients referred directly to ICA. This evidence was not applicable to VA, where practices regarding direct referral to ICA and the use of CCTA differ from those in community settings. The review also did not find compelling evidence that using CCTA plus HeartFlow would reduce ICA use in patients who undergo other types of non-invasive testing for suspected coronary disease.

Updated synthesis of the evidence

ESP investigators conducted the current review to provide an updated synthesis of the evidence on the use of HeartFlow for the non-invasive diagnosis of CAD, focusing on evidence that is most relevant to VA and most applicable to evidence gaps identified in the 2019 ESP review. Investigators searched MEDLINE®, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials, in addition to other sources up to February 2021. The updated review included 24 studies on HeartFlow use in patients with suspected CAD.

Summary of Findings

New evidence did not resolve the evidence gaps identified in the 2019 ESP report. There was no new evidence that examined HeartFlow use in patients directly referred to ICA or as a substitute for other non-invasive testing. New evidence agreed with the previous finding that HeartFlow likely has good diagnostic accuracy for identifying obstructive CAD. New evidence also agreed with the previous finding that short-term rates of cardiac events are similar in those receiving HeartFlow and those receiving other diagnostic strategies, but research on longer-term clinical outcomes is needed. New evidence comparing ICA use in patients undergoing CCTA alone or HeartFlow had severe methodological limitations. CCTA use within VA remains relatively low and is unlikely to change without direct evidence that a CCTA-based strategy is preferable to other non-invasive strategies.

Implications

In the US, many major medical centers use HeartFlow, and the Centers for Medicare and Medicaid Services (CMS) and several commercial payers cover the use of HeartFlow in specific clinical situations. VA does not currently have guidelines or coverage policies regarding the use of HeartFlow FFRCT analysis. This updated review of the literature suggests that the impact of regularly using HeartFlow for all patients referred for CCTA within VA is likely low, but the use of HeartFlow in facilities that regularly utilize CCTA – and in specific clinical scenarios – could potentially reduce the unnecessary use of invasive coronary angiography (ICA). Research in VA settings and comparing HeartFlow to specific non-invasive strategies is needed to determine the potential impact of HeartFlow within the VA healthcare system.

Research Gaps/Future Research

Substantial gaps in the evidence remain. Most importantly, no studies have assessed HeartFlow in a VA setting. The utility of HeartFlow depends on the characteristics of patients who undergo diagnostic testing and on how clinical decisions are made within a particular setting. Patient characteristics and clinical pathways may differ between non-VA and VA populations and settings, and the impact of HeartFlow within VA remains unknown. Moreover, clinical decisions and diagnostic pathways likely differ within VA compared to those in community settings in studies of HeartFlow, and direct evidence about how HeartFlow compares to diagnostic tests widely used in VA is needed. Additionally, only a single study (with serious methodological limitations) examined the impact on ICA use of adding HeartFlow to the clinical pathway for patients referred for CCTA, which is the clinical scenario promoted on the manufacturer website. Controlled studies of ICA rates in patients with suspected coronary disease receiving CCTA or other non-invasive strategies – and comparing HeartFlow to specific non-invasive strategies are needed.

Anderson J, Young S, Helfand M. Evidence Brief: Coronary Computed Tomography Angiography with Fractional Flow Reserve in Noninvasive Diagnosis of Coronary Artery Disease. Washington, DC: Evidence Synthesis Program, Health Services Research and Development Service, Office of Research and Development, Department of Veterans Affairs. VA ESP Project #09-199; 2021.

To view the full report, go to https://www.hsrd.research.va.gov/publications/esp/HeartFlow-FFRCT-brief.cfm

ESP is currently soliciting review topics from the broader VA community. Nominations will be accepted electronically using the online Topic Submission Form. If your topic is selected for a synthesis, you will be contacted by an ESP Center to refine the questions and determine a timeline for the report.

This Management e-Brief is provided to inform you about recent HSR&D findings that may be of interest. The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs. If you have any questions or comments about this Brief, please email CIDER. The Center for Information Dissemination and Education Resources (CIDER) is a VA HSR&D Resource Center charged with disseminating important HSR&D findings and information to policy makers, managers, clinicians, and researchers working to improve the health and care of Veterans.

This report is a product of VA/HSR&D's Evidence Synthesis Program (ESP), which was established to provide timely and accurate synthesis of targeted healthcare topics of particular importance to VA managers and policymakers –; and to disseminate these reports throughout VA.

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