An Observational Study assessing the value of Computed Tomography Cardiac Angiography (CTCA) in planning invasive angiographic procedures in patients with previous coronary artery bypass grafting (CABG).

Aims: Invasive coronary angiography (ICA) is more complex and challenging in patients with previous coronary artery bypass grafts (CABG). Computed tomography coronary angiography (CTCA) may provide useful information prior to ICA to improve these procedures. This study aimed to see if upfront CTCA prior to coronary angiography can reduce contrast load, procedural duration, and procedural complications compared to ICA alone. Methods and results: This single-centre observational study included 835 patients with prior CABG undergoing invasive coronary angiography. One hundred and six patients underwent CTCA prior to ICA and were compared to 729 patients undergoing conventional coronary angiography alone (control group). No significant differences were seen between the two groups in patient demographics and procedural characteristics (number of bypass grafts), and interventional cardiologists' experience. The CTCA group had lower contrast volumes (171.3 vs 287.4 ml, p<0.0001), radiation doses (effective dose 4.6 vs 10.5 mSv, p<0.0001) and procedure times (fluorosocopy time 9.5 vs 12.6 min, p<0.0001) at the time of ICA compared to patients who did not have prior CTCA. Combined radiation doses (ICA+CTCA) versus ICA alone were similar (p=0.867) with significant reductions in overall contrast used seen in the CTCA group (p=0.005). Complete diagnostic studies were performed in all patients with prior CTCA (106 patients, 100%) compared to 543 patients (74.64%, p=<0.0001) without previous CTCA. As a result, 34 patients (4.4%) went on to have CTCA post angiography due to missed grafts. Of these, four needed further invasive angiographic assessment and subsequent coronary intervention following the CTCA scan. Conclusions: Prior CTCA improves graft detection at the time of coronary angiography and reduces the time necessary to localise graft ostium, the total procedure time, and volume of contrast media used.