PURPOSE
To assess feasibility and diagnostic accuracy of one-stop, low iodine 64-row CT coronary angiography (CTCA) performed with the same imaging protocol used for treatment planning in detecting significant coronary artery disease (CAD) in patients with severe aortic stenosis candidate to TAVI.

MATERIALS AND METHODS
From January 2017 to June 2018, 95 TAVI candidates underwent multidetector CT angiography (MDCTA) for TAVI planning on a high definition 64-row CT scanner. Following an ECG-ungated thoraco-abdominal MDCTA acquisition for the evaluation of potential vascular access routes, a single retrospectively ECG-gated CTCA acquisition was performed for annular sizing and to rule out significant (≥50% lumen narrowing) coronary stenosis using a low iodine concentration (270mgI/mL) contrast injection protocol. CTCA was considered positive in presence of inconclusive findings or of at least one significant stenosis of the left main artery (LMA) and/or the proximal segment of the left anterior descending (LAD), circumflex (CX) or right coronary (RCA) arteries.

RESULTS
Per-patient sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of CTCA versus ICA as gold standard were 100%, 60%, 65.2% and 100%, respectively. On a per-vessel basis, sensitivity and NPV were 100% for the LMA and the proximal segments of LAD, CX and RCA, whereas specificity ranged from 57.7% for proximal RCA to 79.3% for proximal LAD. Agatston score showed a significant negative correlation with image quality in patients who underwent both CTCA and ICA (rs=-0.6879, p<0.0001), but not in those who forwent ICA (rs=-0.1936, p=0.2186) due to negative pre-procedural CTCA findings. Iodine load for CTCA acquisitions was 9.4-13.5 gI. No complications occurred immediately after CTCA.

CONCLUSIONS
One-stop high definition 64-row CTCA with a low iodine protocol is feasible for pre-procedural coronary assessment in TAVI candidates and could reliably serve as a gatekeeper to ICA owing to its high effectiveness in detecting significant CAD.