Background Thromboembolic complications occur more frequently in patients with chronic heart failure (CHF) than in the general population. Formation of a compact fibrin clot resistant to lysis has been shown in arterial and venous thrombosis.

Objective To investigate fibrin clot properties in patients with CHF.

Method Plasma clot permeability, compaction, turbidity and fibrinolysis were assessed in 36 consecutive patients with stable CHF (30M, 6F; aged 64±10 years, left ventricular ejection fraction (LVEF) 34.9±6.7%) and 36 controls matched for age, sex, cardiovascular risk factors and medication. Exclusion criteria were LVEF >40%, anticoagulant therapy, previous thromboembolic events, atrial fibrillation.

Results Clots obtained from plasma of patients with CHF had 23% lower clot permeability (p<0.0001), 13% less clot compaction (p<0.001), 15% faster fibrin polymerisation (p<0.0001) and tended to have prolonged fibrinolysis time (p=0.1) compared with controls. C-reactive protein and fibrinogen were associated inversely with clot permeability (R²=0.84, p<0.0001 and R²=0.79, p<0.0001, respectively) and positively with fibrinolysis time (R²=0.88, p<0.0001 and R²=0.80, p<0.0001, respectively) in patients with CHF. Plasma thrombin–antithrombin complex concentrations were inversely correlated with clot permeability (R²=0.88, p<0.0001) and positively with fibrinolysis time (R²=0.91, p<0.0001). Left atrium diameter, but not LVEF, correlated with fibrinolysis time (R²=0.61, p=0.027).

Conclusions Patients with CHF with sinus rhythm are characterised by faster formation of compact plasma fibrin clots, which might predispose to thromboembolic complications.