Purpose: To determine the impact of on-site CT-FFR on diagnostic effectiveness, management strategy and downstream invasive coronary angiography (ICA) in patients with suspected CAD.
Methods: 196 patients (59.1 ± 9.6 years, 47% women) with suspected CAD underwent a CCTA in the CRESCENT I and II trials. On-site CT-FFR analysis was performed in all patients with at least one =50% stenosis on CCTA (N=53). We assessed the effect of adding CT-FFR analysis to CCTA in terms of 1) diagnostic effectiveness, i.e. the number of additional tests required to determine the final diagnosis; 2) reclassification of the initial management strategy; 3) ICA efficiency, i.e. ICA rate without =50% CAD.
Results: CT-FFR was calculated in 42/53 (79%) of the eligible patients as it could not be calculated in patients with suspected coronary total occlusion (N=7), severe coronary calcification (N=2), severe CT artefacts (N=1) or missing CT images (N=1). CT-FFR =0.80 was present in 27/196 (14%) patients, including 8/196 (4%) patients with high-risk ischemia (CT-FFR =0.80 in all three vessels, left main or proximal left anterior descending coronary artery). The final diagnosis was achieved with CT-FFR in an additional 30/196 (15%) patients compared to CT alone (p<0.0001), and rendered 42/56 (75%) of additional tests unnecessary (p<0.0001). The initial management strategy was reclassified in 30/196 patients (15%, p<0.0001); 24/196 (12%) patients were reclassified to optimal medical therapy and 6/196 (3%) patients were reclassified directly to ICA including 4/8 (50%) patients with high-risk CAD on ICA. CT-FFR would result in 6/32 (19%, p=0.012) ICA cancellations in which none of the patients had high-risk CAD. The rate of ICA without =50% stenosis would decrease from 22% (7/32) to 11% (3/27) (p=0.012).
Conclusion: Implementation of CT-FFR has the potential for improved diagnostic effectiveness. Functional reclassification of CAD provides more efficient ICA referral in patients with suspected CAD compared to CTA alone.