Factor XI as a risk factor for persistent left ventricular thrombus following acute myocardial infarction

BACKGROUND: Mechanisms behind unresolved left ventricular thrombus (LVT) developed after acute myocardial infarction (MI) are unclear. AIMS: To investigate whether elevated factor (F) XI is associated with persistent LVT following acute MI. METHODS: In consecutive 148 patients (aged 63.9 [6.9] years) with LVT detected during hospitalization for acute MI, all of whom received oral anticoagulation with dual antiplatelet therapy, we assessed FXI levels 3 months post-MI, while off anticoagulation, along with plasma fibrin clot permeability (Ks), clot lysis time, and plasminogen activator inhibitor-1. LVT resolution was evaluated 3 and 6 months post MI. RESULTS: Plasma FXI (median 111.5%, first-third quartile 101.5%-121.0%) weakly correlated inversely with Ks and positively with both clot lysis time and plasminogen activator inhibitor-1 (all P <0.05), without any other associations. Patients with persistent LVT at 3 and 6 months (75 [50.7%] and 44 [29.7%], respectively), as compared with those who achieved thrombus resolution, had higher FXI by 8.3% and 12.1%, respectively (both P <0.05). Elevated FXI (>120%), detected in 42 (28.4%) patients, along with low Ks, predicted LVT persistence solely at 6 months following MI, independently of age, sex, and previous MI/percutaneous coronary intervention (odds ratio, 6.73; 95% confidence interval, 1.92-23.54; P = 0.003). CONCLUSIONS: To our knowledge, this study is the first to demonstrate that elevated FXI may predispose to unresolved LVT post MI while on anticoagulation, which suggests that FXI assessment might help identify patients prone to this complication who could possibly benefit from FXI inhibition in the future.