An investigation of the anatomical variations of left atrial appendage by multidetector computed tomographic coronary angiography.

PURPOSE The left atrial appendage (LAA) is usually known as a long, tubular, hooked structure derived from the left atrium. However, it varies widely in terms of anatomical shape. In this study, anatomical shape variations of the LAA were investigated and classified in vivo in a large group of patients by multidetector computed tomography (MDCT) coronary angiography. MATERIALS AND METHODS The study included 320 consecutive patients (223 men and 97 women, with a mean age of 58 years) who underwent MDCT coronary angiography. MDCT was performed with a 64-detector-row computed tomographic scanner. LAA anatomical variations were classified as five main types and further divided into subtypes. In addition, we gave the classifications descriptive names according to the anatomical external appearance of the LAA: horseshoe (type 1), hand-finger (type 2a), fan (type 2b), wing (type 2c), hook (type 3), wedge (type 4) and swan (type 5) shapes. The types and subtypes of the LAA variations and the presence of thrombus were recorded. RESULTS In our study, the LAA tip orientation was used and the LAA was divided into type 1, type 2a, 2b, 2c, type 3, type 4 and type 5 in 44 (13.8%), 65 (20.3%), 155 (48.4%), 8 (2.5%), 27 (8.4%), 6 (1.9%) and 15 (4.7%) patients, respectively. LAA thrombus was detected in four patients (1.25%), who had classified LAA shapes of type 2a and type 2b. CONCLUSIONS The LAA has multiple anatomical shape variations. We demonstrated previously undefined new shape types of LAA. Knowledge of LAA variations is important in order to avoid procedure-related complications when ablative treatment is to be performed or if surgical procedures are indicated in this region. MDCT coronary angiography provides important and detailed information about determining and evaluating these variations before undertaking a planned procedure in this region.