Introduction There is little difference between CTCA and ICA in the ability to predict ICA fractional flow reverse (FFR) positive stenosis and ICA should follow CTCA to facilitate revascularisation not to ‘check’ CTCA results. This audit determined the proportion of patients having no treatment change (NTC) when ICA followed CTCA in Plymouth Hospitals NHS Trust (PHNT).

Methods A retrospective single site audit identified 292 patients who had both diagnostic quality CTCA and subsequent ICA for the same patient episode between 2013 and 2014. Significant coronary artery disease (CAD) was defined as > 50% stenosis (≥moderate) and ICA was used as the reference standard (deferring to FFR if available). Patients were classified according to whether revascularisation followed ICA, or NTC resulted in which case we identified a main factor why.

Results There was 89% agreement between CTCA and invasive testing. 27/292 (9.25%) patients had CTCA considered false positive and 5/292 (1.71%) false negative (FN) after ICA +/- FFR (33/292 FFR, 11.30%). Most patients were revascularised 168/292 (57.53%, PCI 119/292, (40.75%), CABG 49/292 (16.78%)) with the CTCA report suggesting revascularisation in 157/292 (53.77%). NTC group consisted of 124/292 (42.47%) patients. 53/292 (18.15%) treated with medical therapy, 64/292 (21.92%) had atypical symptoms, 5/292 (1.71%) had complex comorbidities and 2/292 (0.68%) had other reasons.

Conclusion CTCA accuracy was high. However 42% of patients undergoing ICA following CTCA have NTC resulting. A positive CTCA result should therefore prompt consideration of clinical consultation, functional imaging or ICA rather than direct ICA.