Elevated serum lipoprotein(a) is a risk factor for left atrial thrombus in patients with chronic atrial fibrillation: A transesophageal echocardiographic study

Background Patients with chronic atrial fibrillation have an increased risk of thromboembolism. Apoprotein(a) has a structural homology with plasminogen, suggesting that lipoprotein(a) [Lp(a)] may produce thrombogenic effects by modulating the fibrinolytic system. However, the role of Lp(a) level in the formation of left atrial thrombus has not been studied. We sought to evaluate whether Lp(a) is a risk factor for left atrial thrombus in patients with chronic atrial fibrillation. Methods and Results The consecutive series of 150 patients (mean age 67 ± 8 years) with chronic atrial fibrillation underwent transesophageal echocardiography. Left atrial thrombus was diagnosed by transesophageal echocardiography. Clinical, biochemical, and echocardiographic variables were prospectively collected. Univariate analysis showed that patients with left atrial thrombus (n = 29, 19%) had higher frequency of spontaneous echo contrast (93% vs 55%, P < .0001) than patients without left atrial thrombus (n = 121). Patients with left atrial thrombus also had a significantly higher serum concentration of Lp(a) (34.5 ± 24.1 vs 17.9 ± 13.5 mg/dL, P < .0001), a larger left atrium (5.4 ± 0.9 vs 4.8 ± 0.7 cm, P < .001), and a lower left atrial appendage peak flow velocity (11.1 ± 5.4 vs 23.5 ± 14.6 cm/s, P < .0001). Multivariate regression analysis showed that the Lp(a) concentration (P < .0001) was a significant positive predictor and the left atrial appendage peak flow velocity (P = .0125) was a significant negative predictor of left atrial thrombus. Left atrial thrombus was present in 16 (48%) of 33 patients with Lp(a) level ≥30 mg/dL. Conclusions Elevated serum levels of Lp(a) are strongly associated with left atrial thrombus. These findings suggest that Lp(a) level may be a novel risk factor for left atrial thrombus in patients with chronic atrial fibrillation. (Am Heart J 1998;136:965-71.)