Observations from a real-time, iFR-FFR "hybrid approach" in patients with severe aortic stenosis and coronary artery disease undergoing TAVI

BACKGROUND: The complexity of coronary physiology in presence of severe aortic stenosis (AS) raises concerns about the reliability of pressure-derived indexes in this clinical setting. Furthermore, neither fractional flow reserve (FFR) nor instantaneous wave-free period (iFR) has been validated in AS. Combining iFR and FFR in a tailored decision-making strategy may help to increase simplicity, accuracy and safety of physiology-guided revascularization in AS. METHODS: In this prospective observational study iFR and FFR were measured before and after TAVI during the same procedure in patients with severe AS and concomitant coronary artery disease (CAD). All decisions about revascularization were based on post-TAVI FFR assessment. The best iFR "defer" and "treatment" values were identified according to their baseline negative (NPV) and positive predictive values (PPV) respectively. A post-hoc analysis was then performed to compare the hybrid iFR-FFR approach with the FFR-only strategy. RESULTS: Sixty-two patients underwent pre- and post-TAVI pressure-wire assessment and were included in the analysis. A "defer iFR value" >0.93 yielded a NPV of 98.4% (91.7%-99.9%) to exclude FFR non-significant stenosis (>0.80), and a "treatment iFR value" <0.83 had a PPV of 91.3% (72%-98.9%) to identify FFR-significant stenosis (≤0.80). A hybrid decision-making strategy based on iFR and FFR spared 63% of patients from adenosine, while maintaining 97% overall agreement with FFR lesions classification. CONCLUSION: A hybrid iFR-FFR diagnostic strategy is feasible and safe in patients with severe AS undergoing TAVI and allows to spare the majority of patients from adenosine, while maintaining a high agreement with FFR classification of coronary lesions.