Prevalence and predictors of left atrial thrombus in patients with atrial fibrillation: is transesophageal echocardiography necessary before cardioversion?

BACKGROUND

Systemic embolization threatens patients with atrial fibrillation (AF). The risk is enhanced at the time of cardioversion. Transesophageal echocardiography (TEE) prior to cardioversion to screen for left atrial thrombus (LAT), a marker of high risk for embolization, is recommended for many patients with AF.

OBJECTIVE

To determine clinical and echocardiographic factors associated with LAT formation in AF.

METHODS

Data from 600 consecutive patients with AF undergoing TEE prior to cardioversion for the detection of LAT were analyzed. Clinical, laboratory, and echocardiographic parameters were abstracted from the clinical record.

RESULTS

TEE identified LAT in 70 (11.6%) and dense (LA) spontaneous echo contrast (SEC) in 156 (26%). Baseline characteristics and echocardiographic parameters of patients with or without LAT are compared. A prior myocardial infarction, 21 (29.4 %) vs. 31 (5.8), (p < 0.001); hypertension, 60 (85.7%) vs. 386 (72.8), (p 0.02); CHADS(2) ≥ 2, 56 (80%) vs. 308 (58.1%), (p < 0.001) prevalence was higher in patients with LAT. Patients with LAT had lower ejection fraction 38.2 ± 15.6 vs. 46.2 ± 14.5, (p < 0.001); higher LA diameter 4.98 ± 0.7 vs. 4.52 ± 0.7, (p <0.001); dense LA SEC 44 (62.8) vs. 112 (21.1), (p < 0.001); and low LA appendage emptying velocity 21.7 ± 12.9 vs. 37.5 ± 19.4, (p < 0.001). Multivariate analysis was done, and it revealed that low LA emptying velocity had the strongest independent association with LAT (HR 0.89 [CI 0.83-0.96], p value <0.001.

CONCLUSION

LAT is not an uncommon finding of AF patients prior to cardioversion. The current practice of TEE examination may be justified since neither clinical nor routine 2D echo examinations reliably identify LAT.