Computed Tomography Coronary Physiology-derived Virtual Stenting Guided Revascularization Strategy in Patients With Coronary Artery Disease

Coronary physiology-guided percutaneous coronary intervention (PCI) improves long-term prognosis in large clinical studies, and wire-based physiological assessments (e.g. fractional flow reserve [FFR], instantaneous wave-free ratio [iFR]) are recommended by international guidelines. Although prognosis of patients undergoing PCI has improved in recent decades with the continuous refinement of equipment, tools and techniques, a considerable number of patients presented with anatomically successful PCI results still suffer from functionally unresolved ischemia, which might be the cause for over one-fourth of patients experiencing recurrent angina or adverse events after angiographically successful PCI. Therefore, it is of great clinical importance to achieve complete resolution of ischemia and optimal functional results during the index procedure.

Currently, the post-PCI physiology measurement is one of the effective metrics to quantify residual ischemia, and a suboptimal post-PCI result is strongly associated with worse outcomes. However, PCI optimization based on post-PCI physiology is, to certain extent, a provisional rescue action for a suboptimal index procedure, which may not be fully correctable "after the fact" given selected stents, site of deployment and procedural technique. The resent TARGET-FFR trial demonstrated that post-PCI physiology-guided incremental optimization strategy (PIOS) failed to significantly improve the final physiological results compared to standard angiographic guidance. Therefore, it would be of significant interest if a preprocedural measurement would be able to anticipate to what extent the functional ischemia could be resolved. If residual ischemia estimated from the computation of post-PCI physiology appears to be present, this would help physicians to develop the best strategies while planning the procedure.

The Computed tomography (CT)-derived FFR (CT-FFR) is a novel non-invasive CCTA-based physiological index that has been validated to have good diagnostic accuracy in identifying physiologically significant coronary stenoses compared with FFR as the reference. The CT coronary physiology-derived virtual stenting (CT-VS) based on pre-PCI CCTA angiograms, is an augmented reality (AR) approach that simulates the post-stenting physiology assuming that the specified segment of the treated vessel is successfully dilated by implanting virtual stents. Previous studies have demonstrated the feasibility of optimizing PCI with CT-VS, with high consistency between pre-PCI simulated physiology result by CT-VS and actual post-PCI physiology results. Therefore, the application of CT-VS would help physicians to develop the best strategies while planning the procedure.

However, there is a lack of knowledge regarding the efficacy of this novel physiological index that is available pre-PCI in achieving final post-PCI optimal physiological result. The Trials of "Computed Tomography Coronary Physiology-derived Virtual Stenting Guided Revascularization Strategy in Patients with Coronary Artery Disease (CT-COMPASS)" was designed to assess the efficacy of a CT-VS vs. standard angiographic guidance in achieving post-PCI optimal physiological result (post-PCI FFR≥0.90).

Virtual stenting-guided incremental optimization strategy (VIOS) Protocol: virtual Stenting analysis is conducted based on pre-PCI CCTA angiograms by "Imaging-Heart Team" to determine simulated optimal treatment strategy according VIOS protocol. The details of VIOS protocol are as follows: 1) virtual stent with adequate stent parameters is initially implanted to treat lesion with maximal CT-FFR drop (ΔCT-FFR); 2) if the simulated post-PCI CT-FFR is ≥0.90, no further intervention will be performed, and the simulated optimal treatment strategy is determined. If simulated post-PCI CT-FFR is <0.90, the "Imaging-Heart Team" would then have the following options: a) if there is a CT-FFR drop ≥0.05 across the virtual stented segment(s), the parameters of virtual stent(s) would be optimized (i.e., number of stents, stent diameter, and stent length); b) if there is a CT-FFR drop ≥0.05 across a relatively focal (<20mm) unstented segment (without virtual stenting) which is suitable for further stenting then a further virtual stent would be implanted; c) simulated post-PCI CT-FFR remains <0.90 after steps a and/or b: if either of the above criteria remain, option of further optimization of virtual stent parameters or one more additional virtual stent. Following this, the result will be accepted. d) if the simulated CT-FFR gradient is interpreted to reflect diffuse atherosclerosis with no focal CT-FFR drop, the result is accepted.