Patients scheduled for TAVI tend to form abnormal fibrin clots more resistant to lysis: the impact of age

BACKGROUND: Fibrin accumulation within the stenotic leaflets associated with impaired fibrinolysis was observed in severe aortic stenosis (AS). Little is known about fibrin clot properties in patients scheduled for transcatheter aortic valve implantation (TAVI). AIMS: We investigated whether TAVI patients display a more prothrombotic state, including suppressed fibrinolytic capacity compared to those undergoing surgery. METHODS: We enrolled patients with advanced AS without significant atherosclerotic vascular disease scheduled for TAVI (n = 45) or surgical aortic valve replacement (SAVR, n = 59). Plasma fibrin clot features, including clot permeability (Ks) reflecting an average pore size, and lysis potential (Lys50), along with thrombin generation were determined off anticoagulation within 12 hours before the procedure. RESULTS: TAVI patients compared to SAVR had prolonged Lys50 (median 420 [IQR, interquartile range, 337-480] seconds vs 379 [337-428] seconds; P = 0.045) and formed denser clots, reflected by lower Ks (3.66 [3.05-4.84] vs 4.36 [3.6-5.27] × 10-9 cm2; P = 0.02), but after adjustment for age the latter difference was no longer significant. Apart from age, concomitant diabetes mellitus, or chronic kidney disease, prolonged Lys50 was an independent predictor of indication for TAVI in AS patients on multivariate regression analysis. There was a delayed start of thrombin generation in TAVI patients (lag time, 4.5 [3.8-6.3] minutes vs 4.2 [3.3-4.7] minutes; P = 0.035), without other differences in thrombin generation parameters. CONCLUSIONS: This study is the first to show that patients scheduled for TAVI are characterized by prothrombotic fibrin clot properties including denser fibrin meshwork and more resistant to lysis compared with those undergoing SAVR, which might explain in part increased thromboembolic risk following TAVI.