Frequency and significance of right atrial appendage thrombi in patients with persistent atrial fibrillation or atrial flutter

Atrial fibrillation (AF) and atrial flutter (AFL) are strong atrial thrombosis (THR) risk factors. In recent-onset tachyarrhythmias, the incidence of left atrial appendage (LAA) THR, detected by transesophageal echocardiography (TEE), has been widely studied, ranging from 6% to 18% (AF) and 4% to 11% (AFL). On the contrary, few studies have assessed right atrial appendage (RAA) THR, and there is no information on the relation between the RAA flow characteristics and the presence of RAA THR. The aims of this study were to evaluate the incidence of RAA THR in a population of patients undergoing TEE-guided cardioversion for recent-onset atrial tachyarrhythmias and to analyze RAA Doppler flow and its relation to thrombus formation.

From 1998 to 2012, patients admitted to the emergency department for persistent, non-self-terminating atrial tachyarrhythmia lasting >2 days who gave informed consent for TEE-guided cardioversion were prospectively enrolled in the study. Among 1,042 patients, complete anatomic and functional studies of the LAA and RAA were feasible in 983 (AF, n = 810 [23%]; AFL, n = 173 [5%]). The presence of RAA and LAA THR, appendage emptying velocities, and the presence of severe spontaneous echocardiographic contrast were studied.

The overall incidence of atrial THR was 9.7% (96 of 983). The incidence of THR was 9.3% (91 of 983) in the LAA and 0.73% (seven of 983) in the RAA (P < .01). In the AF and AFL groups, the incidence of LAA THR was 10.3% (83 of 805), compared with 0.75% (six of 805) for RAA THR (P < .01). Among patients with AFL, the incidence of LAA THR was 6% (10 of 178), compared with 0.6% (one of 178) for RAA THR (P < .01). The mean LAA peak emptying velocity was 24 cm/sec (range, 10-32 cm/sec) in patients with LAA THR, compared with 38 cm/sec (range, 20-59 cm/sec) in those without THR; the mean RAA peak emptying velocity was 17 ± 7 cm/sec in patients with RAA THR, compared with 34 ± 13 cm/sec in those without THR (P < .001).

RAA thrombi are significantly less frequent than LAA thrombi but may reach large dimensions. Multiplane TEE allows RAA morphologic and functional assessment. Before TEE-guided cardioversion, both the LAA and the RAA must be routinely studied.