Plasma fibrin clot properties affect blood loss after surgical aortic valve replacement for aortic stenosis.

Abstract

Cardiac surgery is associated with elevated bleeding risk. We sought to study whether fibrin clot phenotype influences postoperative blood loss after surgery for aortic stenosis (AS). We studied 77 isolated AS patients, including 62 who underwent aortic valve replacement and 15 who underwent the Bentall procedure due to post-stenotic aortic dilation. Plasma clot properties, including the tPA-induced clot lysis time (CLT) and clot permeability (Ks), along with fibrinolysis inhibitors, a calibrated automated thrombogram and platelet activation markers, were assessed preoperatively. In the whole AS group, the median chest tube output after 12 h was 360 ml (range of 110-2290 ml). Patients with drainage in the top quartile after 12 h (≥600 ml) had lower fibrinogen, shorter CLT, higher Ks, lower plasma plasminogen activator inhibitor-1 antigen, peak thrombin generation and β-thromboglobulin levels than those in the lowest drainage quartile (≤260 ml) with no difference in platelets or von Willebrand factor. A multivariable model that was built after the exclusion of Bentall patients, adjusted for age, sex, body mass index and fibrinogen, showed that high drainage, which was defined as the top quartile after 12 h postaortic valve replacement (≥460 ml), was predicted by β-thromboglobulin [odds ratio (OR) 0.94, 95% confidence interval (CI) 0.90-0.99, P = 0.03], fibrinogen (OR 0.13, 95% CI 0.00-0.47, P = 0.02) and the CLT (OR 0.95, 95% CI 0.91-0.99, P = 0.02). The CLT was inversely related to the number of transfused platelet units (r = -0.27, P = 0.04). Fibrin clot susceptibility to lysis is a modulator of postoperative blood loss after cardiac surgery for AS, which may have practical implications.