Intraprocedural cardiac computed tomography-fluoroscopy image fusion guided structural heart intervention: a proof of concept experience during transcatheter aortic valve implantation

Intraoperative image guidance using cardiac CT with fluoroscopy image fusion has been shown to facilitate structural heart interventions. However, there has been limited experience on CT image fusion with fluoroscopy using aortic root calcifications from intraoperative 3D cone-beam CT imaging. This study aims to evaluate the technical feasibility, safety and clinical outcomes of consecutive patient population who underwent TAVR procedure with CT fusion imaging after acquiring intra-operative cone-beam CT imaging as compared to those who underwent TAVR without CT fusion during the same period. This retrospective study included patients who underwent TAVR procedure during the early learning experience at our institution whom CT image fusion was performed after acquiring a non-contrast intraprocedural cone-beam CT imaging under rapid-pacing and breath-hold. Reconstructed non-contrast images of aortic root from cone-beam CT was fused with pre-procedural CT imaging after aligning the aortic-root calcifications between both the 3D datasets. Between 2012 and 2014, a total of 164 patients underwent TAVR procedure, of whom 96 underwent 3D-3D CT image fusion. There were no significant differences between the two study groups for any perioperative events or length of stay. However, the CT fusion group had significantly fewer total aortic root angiograms performed, with a risk difference of -23.3% [-38.0%; -8.0%], p = 0.002, and a relative risk of 0.67 [0.49; 0.85], p < 0.001. Contrast volume was not different between both groups (p = 0.09) but there was a trend toward less contrast use during early TAVR experience. The CT fusion group had lower total Air Kerma (p = 0.04) but no significant difference in dose-area product (p = 0.06) Among patients with peripheral vascular disease (PVD), patients who underwent CT fusion had fewer peri-operative complications than patients who did not undergo CT fusion (80% vs. 10.5%, p = 0.007). This proof-of-concept study reveals that TAVR patients with aortic root calcifications-based CT image fusion underwent fewer aortic root angiograms at appropriate C-arm angulations derived from intra-procedural 3D imaging, thereby accounting for patient positioning differences. There was a trend to use less radiation and contrast volume in the fusion group with early TAVR experience, that gradually subsided over time, likely secondary to increased operator experience. However, there were no differences in perioperative events or length of stay between TAVR with or without CT fusion, except among patients with PVD. Further studies are needed to investigate the potential benefits of intra-procedural CT image fusion.