Changes in microcirculation following transcatheter aortic valve implantation in patients with stable coronary artery disease

BACKGROUND: Few studies have assessed coronary physiology in the setting of coronary artery disease (CAD) with severe aortic stenosis (AS). Fractional flow reserve (FFR) to guide revascularization in such patients is not validated. AIMS: We describe changes in coronary physiology in this population before and after transcatheter aortic valve implantation (TAVI). METHODS: Patients with stable CAD and severe AS treated with TAVI were prospectively included during 2020-2023. Coronary physiology was assessed before and immediately after TAVI, and at follow-up (median 5.4 months). RESULTS: Twenty-nine patients (mean age 81.3 years) were included. Median (95% confidence interval) FFR decreased numerically, from 0.83 (0.79-0.84) pre-TAVI to 0.81 (0.78-0.83) post-TAVI. During hyperaemia, the transit mean time reduced numerically, from 0.27 (0.19-0.35) to 0.20 (0.18-0.27) seconds, reflecting increased coronary flow. Basal microvascular resistance increased numerically, from 24 (21-35) to 32 (23-45), while resistive reserve ratio increased significantly, from 1.8 (1.5-2.3) to 2.6 (2.2-3.1) (P=0.002). Consequently, coronary flow reserve (CFR) improved significantly, from 1.5 (1.2-1.7) to 1.9 (1.5-2.4) (P=0.006). Among 21 patients with follow-up, no significant change in FFR was observed and the significance of the increase in CFR was lost. Only three patients had an index of microvascular resistance>25, indicating microvascular impairment during hyperaemia. CONCLUSIONS: In stable CAD patients treated with TAVI for severe AS, valve replacement provides an immediate improvement in CFR. FFR shows a minimal decrease after valve implantation, supporting its reproducibility to guide revascularization in such patients. CLINICAL TRIAL REGISTRATION: .NCT04663334.