Journal Article

152 Ct-derived fractional flow reserve – outcomes from a district general hospital-led service

Farag, Ahmed, Kasolo, Yande

2022

Overview

ObjectivesAs stipulated by the 2016 NICE Chest Pain of recent onset guidelines, Computed Tomography Coronary Angiography (CTCA) is the recommended first line investigation when stable angina cannot be excluded by clinical assessment alone (1). Non-invasive Computed Fractional Flow Reserve (CT-FFR; Heartflow) is a method which utilises CT data as a diagnostic tool in identification of patients that may benefit from coronary revascularisation (2). We aimed to evaluate the diagnostic utility of CT-FFR in a district general setting in predicting significant coronary disease, defined as a positive functional test or the need for revascularisation (percutaneous or coronary artery bypass grafting).Method:This was a single centre, retrospective study of patients who had CTCA with subsequent FFR analysis from July 2019 to February 2021 (n=106). Electronic records were used to determine subsequent downstream testing and revascularisation. Lesions were documented as concordant or discordant; the former indicating an FFR result that was in keeping with the reported anatomical severity and the latter indicated discrepant results. Due to the intermediate nature of CAD-RADS 3 results, CT-FFR findings could not be defined as either concordant or discordant. Positive and negative predictive values of both CTCA and CT-FFR in identifying significant coronary pathology were calculated.Results:106 patients underwent CTCA with FFR analysis. 15 were excluded from this study due to suboptimal image quality preventing reliable FFR results. The Positive Predictive Value (PPV) and Negative Predictive Value (NPV) for CTCA alone in predicting functionally significant coronary disease was 41.3% and 86.9%, respectively. When the CAD-RADS 3 cohort was eliminated, PPV increased to 71.4% and the NPV remained unchanged (86.9%). The combination of CTCA with FFR gives a Positive and Negative Predictive Value of 48.4% and 83.3%, respectively. With elimination of the CAD-RADS 3 group, PPV was 85.7% and NPV of 80%.Abstract 152 Figure 1Revascularisation in the discordant and concordant CT-FFR groupsAbstract 152 Figure 2Outcomes of FFR analysis in the CAD-RADS 3 cohortConclusionAs supported by previously published literature, the negative predictive value of both CTCA in isolation, and when combined with FFR remains consistently reliable. Our study demonstrated that the positive predictive value is less reliable for both tests and supports the notion that these tests tend to over-estimate the severity of coronary lesions. However, at the extremes of the CAD-RADS spectrum, PPV is a much more robust variable, as highlighted by the increase in this value when CAD-RADS 3 results are removed from the cohort. This reiterates the importance of not letting test results detract from robust clinical assessment and symptom correlation, particularly in the context of discordant or intermediate results.References1. National Institute for health and care excellence (NICE) guidance for the assessment and diagnosis of recent-onset chest pain of suspected cardiac origin (clinical guideline 95 (CG95)).2. Pijls NH, van Schaardenburgh P, Manoharan G, et al. Percutaneous coronary intervention of functionally non-significant stenosis: 5-year follow-up of the defer study. J Am Coll Cardiol. 2007;49:2105–2111.Conflict of Interestnone

• Publisher: BMJ Publishing Group Ltd and British Cardiovascular Society,BMJ Publishing Group LTD
• Subject: Body fat / Cardiomyopathy / Conflicts of interest / CTCA / Diabetes / FFR / Imaging / Magnetic resonance imaging / revascularisation / Tomography