Lipoprotein (a) as a risk factor for prosthetic heart valve thrombosis

Genetic and numerous epidemiologic studies have identified lipoprotein (a) [Lp(a)] as a risk factor for atherothrombotic diseases. The structure of Lp(a) is similar to plasminogen and tissue plasminogen activator and it competes with plasminogen for its binding site, leading to reduced fibrinolysis. Furthermore, since Lp(a) stimulates the secretion of plasminogen activator inhibitor-1, it may lead to thrombogenesis. In this cross-sectional study, we aimed to investigate Lp(a) levels in patients with mechanical prosthetic valve thrombosis (MPVT). Blood samples for Lp(a) determination were obtained from 80 MPVT patients (median age: 48.5 (39-59.75) years; 47 male) and 75 age and sex matched controls (median age: 52 (39-63) years; 44 male) with normally functioning mechanical prosthetic valves. The Lp(a) levels in the PVT group were significantly higher than in the controls [22(16.2-39.4) vs. 6.9(2.9-24.6) mg/dL, p < 0.001]. Elevated Lp(a) levels, recent history of subtherapeutic anticoagulation, history of cerebrovascular accidents (CVA) and a low value of international normalized ratio on admission were found to be the independent predictors of PVT. Lp(a) levels above 19.6 mg/dL predicted PVT with a sensitivity of 65% and a specificity of 71% (AUC:0.767; 95%CI: 0.687 to 0.847; p < 0.001). Lp(a) levels were significantly higher in PVT patients with a history of CVA [42.0 (23.6-53.6) vs. 21.1 (16.1- 36.2) mg/dL, p = 0.012]. Elevated Lp(a) levels may be associated with MPVT. The assessment of plasma Lp(a) levels in patients with prosthetic heart valves may provide additive information regarding the risk of PVT and CVA.