Influence of physiological patterns of coronary disease on fractional flow reserve and instantaneous wave-free ratio changes in patients undergoing TAVI

Background: Inconsistent variations of hyperaemic and resting physiology indexes have been reported between pre- and post-transcatheter aortic valve implantation (TAVI). Aims: This study aimed to evaluate the predominant physiological pattern of coronary artery disease (CAD) in patients with severe aortic stenosis (SAS) undergoing TAVI and assess its impact on fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) variations between pre- and post-TAVI. Methods: Patients with SAS and CAD undergoing FFR and iFR assessment before and after TAVI were included. Vessels were categorized based on FFR and iFR tertiles of change. Longitudinal vessel analysis using Murray's law-based quantitative flow ratio (mu FR) was performed. Disease pattern was considered focal with mu FR-pullback pressure gradient index (mu FR-PPGi) >= 0.78, and local disease severity was stratified by instantaneous mu FR gradient per unit length (d mu FR/ds) with a value of 0.025/mm. Results: In total, 136 vessels (67 patients) were assessed with mu FR, having paired pre- and post-TAVI FFR and iFR. mu FR-PPGi was 0.73 +/- 0.13, with 60.3 % showing diffuse CAD. d mu FR/ds was 0.03 +/- 0.03/mm, with 27.2 % having a major gradient. Vessels with decreased FFR post-TAVI had lower pre-TAVI FFR and higher d mu FR/ds compared to stable or increased FFR vessels. iFR changes were unpredictable; both decreased and increased iFR vessels post-TAVI had lower pre-TAVI FFR and iFR values and showed major d mu FR/ds gradients. Conclusions: In SAS patients undergoing TAVI, diffuse CAD without major gradients was the predominant physiological pattern. Post-TAVI, FFR typically decreased in vessels with major focal gradients, while iFR changes were more unpredictable.