F11 and venous thromboembolism: Patients with lower levels of FXI are at less risk of venous thromboembolism (VTE) and MI43and FXI level is correlated with MI risk among men in the study of Myocardial Infarction Leiden.44Butenas et al reported that plasma FXIa level could be quantified in most patients with ACSs, whereas it was undetectable in age-matched healthy controls.45However, conflicting data exist.