Left atrial volume assessed by ECG-gated computed tomography: Variations according to age, gender and time during the cardiac cycle.

PURPOSE: The purpose of this study was to retrospectively assess the accuracy of the maximal left atrial volume (LAVmax ) measured at 75% of the cardiac cycle compared to the 40% measurements and to evaluate this volume according to age and gender.

PATIENTS AND METHOD: A total of 150 patients with a mean age of 50±17 (SD) years (range: 21-79 years) were analyzed. There were 78 men and 72 women. LAVmax were measured from retrospective triphasic cardiac-gated multi-detector computed tomography (MDCT) data at the 40% (LAV40 ) and 75% (LAV75 ) of the RR cycle phases by a semi-automatic method.

RESULTS: LAV40 was 50.7±14mL/m2 and LAV75 was 42.5±13mL/m2 . The difference was statistically significant. Considering the reference range of LAVmax reported in the literature, 33% of the patients had enlarged LA with LAV40 and only 17% with LAV75 . These volumes were positively influenced by age but not by gender. The relationship between LAV75 and LAV40 was: LAV75 =0.908 LAV40 -3.486 (r2 =0.92) or LAV40 =1.1×LAV75 +3.8 (r2 =0.92).

CONCLUSION: LAVmax measured at the 75% of the cardiac cycle phase significantly underestimates actual LAV leading to reconsider normal values. LAV40 can be computed from the measured value of LAV75 obtained on prospective ECG-gated MDCT.