Analysis of left atrial appendix by dual-source CT coronary angiography: Morphologic classification and imaging by volume rendered CT images

Abstract

We investigated the evaluability of left atrial appendix by dual source coronary CT angiography and analyzed morphologic features. We included 106 consecutive patients who underwent coronary CT angiography for various indications. Technical parameters were slice thickness 0.6 mm, reconstruction interval 0.3mm, gantry rotation time 165 ms. Images were reconstructed from 10% to 100% R-R intervals at 10% intervals to evaluate the left atrial appendix and 4-D inspace software was used for analysis. We recorded the R-R intervals when the left atrial appendix was at maximum and minimum volume. We also evaluated visibility of appendix at R-R intervals. Maximum appendix volume was calculated. Atrial appendices were classified morphologically based on number of chambers (types 1-3) seen on volume rendered images. There were 60 male and 46 female patients in the study group and, mean age was 55±13. Mean heart rate was 72 (ranges 47-110). Left atrial was evaluable at maximum and minimum volume by coronary CT angiography in all patients. We noted types 1-3 appendix in 29 (27%), 73 (69%), and 4 (4%) patients, respectively. Mean R-R intervals at maximum and minimum volume were 40%±6 (95% CI; 28-52%) and 95%±5 (95% CI; 85-5%), respectively. Mean appendix maximum volume was 7±4 cm3. Appendix contours were mildly, moderately and severely irregular in 10 (9%), 58 (55%), 38 (36%) patients, respectively. Left atrial appendix was visualized in all patients independent of heart rate at maximum and minimum volumes. Volume rendered CT images can allow excellent depiction of left atrial appendix morphology and classification. Presence of moderate and severe irregularity of appendix contour in most of the patients may be the cause of slow flow. This morphologic appearance may be the underlying reason for the propensity to atrial appendix thrombus formation.