Accessory appendages of the left atrium as seen during 64-slice coronary CT angiography.

Purpose: To document the frequency and variations in number and anatomical shape of accessory appendages of the left atrium as seen on 64-slice cardiac CT.

Methods And Materials: Retrospective review of the anatomy of the left atrium as depicted by cardiac CT using the acquisition protocol designed for coronary CT Angiography and performed in 166 patients over a 6-month period with a 64-slice ECG-gated CT scanner (Siemens Medical Solutions). The local IRB provided a waiver of informed consent for this retrospective study. Structures less than 5 mm in shape were excluded, as well as large accessory pulmonary veins.

Results: Seventeen (17) of 166 patients (10%) had 18 accessory left atrial appendages (only one patient had two). Fifteen (15) accessory appendages were located along the right upper atrial wall and measured 0.9 x 0.6 x 0.5 cm(3) +/- 0.2 x 0.2 x 0.1 (Type 1). Three (3) were located along the left lower atrial wall, and were larger (0.9-2.5 cm cross-section) (Type 2). The right upper accessory appendages were mostly shaped like small diverticuli and the left lower ones were shaped like flat cauliflower expansions.

Conclusions: Accessory left atrial appendages were visualized in 10% of 166 patients during 64-slice coronary CT angiography.