TEE for Low-Risk Atrial Fibrillation Patients
ABSTRACT & COMMENTARY
Synopsis: A good history was more important than TEE for the assessment of embolic risk in outpatients with atrial fibrillation.
Source: Stöllberger C, et al. Ann Intern Med 1998; 128:630-638.
Although transesophageal echocardiography (TEE) can detect left atrial thrombi, stasis (spontaneous contrast), and appendage enlargement, its value in predicting the risk of stroke and its prevention is unclear. Thus, the Embolism in Left Atrial Thrombi (ELAT) study group report is of interest. They studied 409 outpatients with constant or intermittent atrial fibrillation (AF) without rheumatic valvular disease or prior stroke within the past year by TEE. Primary end points were stroke and systemic emboli; secondary end points included non-stroke death and need for anticoagulation over two years. The study was designed to be observational, but for ethical reasons patients with atrial thrombi were advised to take anticoagulation and the remaining patients aspirin. Atrial thrombi were noted in 10 patients (2.5%) and spontaneous echo contrast (SEC) in 47 (12%). After a mean follow-up of 58 months, stroke or embolism occurred in 50, 38 required anticoagulation, and 53 died of non-embolic causes. Univariate analysis showed that atrial thrombi (risk ratio [RR], 3.9), appendage size (RR, 1.6-2.4), and valvular abnormalities (1.9) predicted stroke or emboli. However, multivariate analysis identified only hypertension (3.6), previous stroke (3.7), and age (1.1) as significant predictors. Stöllberger and associates conclude that a good history was more important than TEE for the assessment of embolic risk in outpatients with atrial fibrillation.
COMMENT BY MICHAEL H. CRAWFORD, MD
This observational outpatient study suffered from a low prevalence of atrial thrombi (2%), SEC (12%), and a low incidence of embolic events (13%). Thus, the power of the study was limited. Also, this was a low-risk group of relatively young patients (mean age, 62 years) with a high incidence of intermittent AF (39%) and lone AF patients (27%). In addition, patients with overt valvular disease were excluded. Consequently, the results are not surprising but are a blow to the proponents of TEE for AF.
The results indirectly suggest that their treatment strategy of aspirin alone for most of these patients was successful. Of the 10 patients with thrombus, seven received anticoagulants. If these 10 patients had only received aspirin, a few may have had embolic events, which would not have changed the results of the study much. Thus, anticoagulation therapy was not a major factor in this study, and aspirin therapy seems appropriate for young, low-risk patients.
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