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

Abstract

BackgroundInconsistent variations of hyperaemic and resting physiology indexes have been reported between pre- and post-transcatheter aortic valve implantation (TAVI). AimsThis 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. MethodsPatients 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 (μFR) was performed. Disease pattern was considered focal with μFR-pullback pressure gradient index (μFR-PPGi) ≥0.78, and local disease severity was stratified by instantaneous μFR gradient per unit length (dμFR/ds) with a value of 0.025/mm. ResultsIn total, 136 vessels (67 patients) were assessed with μFR, having paired pre- and post-TAVI FFR and iFR. μFR-PPGi was 0.73 ± 0.13, with 60.3 % showing diffuse CAD. dμFR/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 dμFR/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 dμFR/ds gradients. ConclusionsIn 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.