Lipoprotein(a), left atrial appendage function and thromboembolic risk in patients with chronic nonvalvular atrial fibrillation

Lipoprotein(a) (Lp(a)) has a prothrombotic effect by modulating the fibrinolytic system. The purpose of the present study was to determine whether serum Lp(a) levels are associated with an increased risk of thromboembolism in chronic nonvalvular atrial fibrillation (NVAF). Clinical, laboratory and transesophageal echocardiographic data were collected in 172 consecutive, non-anticoagulated patients with chronic NVAF. Thirty-four patients (thromboembolic group) had a recent (<1 month) embolic event and/or a left atrial thrombus on transesophageal echocardiography. The thromboembolic group had a higher frequency of spontaneous echo contrast (94 vs 58%, p<0.0001), increased concentrations of Lp(a) (median: 31.5 vs 15.5 mg/dl, p<0.0001) and fibrinogen (median: 352 vs 314 mg/dl, p=0.0015), larger left atrial dimensions (median, 5.1 vs 4.8 cm, p=0.0078), and reduced left atrial appendage (LAA) flow velocities (median: 9.5 vs 21.2 cm/s, p<0.0001) than the nonthromboembolic group. Multivariate analysis identified 3 independent predictors of thromboembolism: Lp(a) level greater than or equal to 30 mg/dl (odds ratio (OR) 9.5, 95% confidence interval (CI) 4.4-20.4, p<0.0001), LAA flow velocity of <20 cm/s (OR 8.7, 95% CI 3.3-23.0, p=0.0003) and a fibrinogen concentration of <377 mg/dl (OR 3.2, 95% CI 1.5-6.9, p=0.0201). The Lp(a) elevations and reduced LAA flow velocities are independently associated with thromboembolism in chronic NVAF.