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

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.