Importance of left atrial appendage flow as a predictor of thromboembolic events in patients with atrial fibrillation

Abstract

Aim. The purpose of this study was to investigate the role of transoesophageal echocardiography in predicting subsequent thromboembolic events in patients with atrial fibrillation. Methods and patients. Transoesophageal echocardiography was performed in 88 patients with documented paroxysmal (n = 53) or chronic atrial fibrillation (n = 35) to assess morphological and functional predictors of thromboembolic events. Prospective selection was from patients with non-valvular atrial fibrillation who had undergone transoesophageal echocardiography because of previous thromboembolism (n = 30); prior to electrical cardioversion (n = 31); or for other reasons (n = 27). All patients were followed up for 1 year. Results. During the period of follow-up new thromboembolic events occurred in 18 of 88 patients (20%/year); 16 of these patients had a stroke and two a peripheral embolism. Univariate analysis revealed that previous thromboembolism (P < 0.005; odds ratio 5.3 [CI 1.9, 12.1]), history of hypertension (P < 0.01; odds ratio 4.0 [CI 1.4, 10.4), presence of left atrial spontaneous echo contrast (P < 0.025; odds ratio 3.5 [CI 1.2, 10.0]), and presence of left atrial appendage peak velocity ≤ 0.20 m.s-1 (P < 0.01; odds ratio 4.1 [CI 1.4, 11.6]) were significantly related to subsequent thromboembolic events. Stepwise logistic regression showed that independent predictors of thromboembolic events were: history of thromboembolism (P < 0.005), history of hypertension (P < 0.05) and low left atrial appendage peak velocity ≤ 0.20 m.s-1 (P < 0.01). Conclusions. In patients with atrial fibrillation, the presence of spontaneous echo contrast in the left atrium, and in particular a low left atrial appendage peak flow velocity, can be used to identify a subgroup of atrial fibrillation patients at either increased or decreased risk of subsequent thromboembolism, which might have important implications for anticoagulation therapy.