Comparison of Electrocardiogram-gated vs. Non-gated Computed Tomography on Image Quality and Measurement Reproducibility in Pre Transcatheter Aortic Valve Replacement Evaluation.

Background
ECG-gated computed tomography angiography (CTA) imaging is a key tool for pre-procedural transcatheter aortic valve replacement (TAVR) planning but is often challenging to acquire in this population. We tested whether non-gated CTA images would compare favorably to gated images and evaluated the impact of using those images for valve selection.

Methods
110 consecutive patients at the University of North Carolina underwent CTA-TAVR evaluation. Both gated and non-gated acquisitions were analyzed by two blinded physician readers who obtained standard pre-TAVR measurements. Inter-reader variability was calculated to ensure homogeneity. Implanted valve size was compared to the valve size recommend by the non-gated and gated aortic annular measurement. Subgroup analysis of valve type and size was performed.

Results
Measurements of the non-gated and gated scans compared favorably and were highly reproducible between readers R² = 0.92 (Figure 1). Compared to TAVR valve implanted, the non-gated and gated scans correctly predicted valve size 83% and 85% of the time, respectively. In subgroup analysis, predicted non-gated valve size agreed more frequently with the balloon-expandable valve (90%) then self-expanding valves (75%). This was similar to the gated predicted valve sizing (balloon-expanding 95%, self-expanding 73%).

Conclusions
This study demonstrates the feasibility of using a non-gated acquisition to obtain standard pre-TAVR measurements with similar diagnostic utility. Clinical factors outside of annular sizing were not taken into account in this study and likely contributed to the percentage of incorrectly sized valves.