MORPHOLOGY: ATRIAL DIMENSIONS Determination of normal gender-specific left atrial dimensions by cardiovascular magnetic resonance imaging

Background. Because cardiovascular magnetic resonance imaging (CMR) is becoming increasingly available in clinical practice, there is a need to establish normal values for left atrial dimensions as determined by this method to allow accurate assessment of cardiac dimensions and to provide standardization for follow up studies. For clinical purpose measurements of the left atrial end diastolic diameter (LAEDD) are most appropriate to assess left atrial size. We aimed to establish normal values for LAEDD using CMR and a fast gradient-echo sequence with steady-state free precession (SSFP). Methods. A total of 111 healthy subjects (52 women and 59 men, mean age 51.5 ± 14.5 years) were examined by CMR. Images were acquired using SSFP in the horizontal (HLA) and vertical (VLA) long axis planes and the left ventricular outflow tract plane (LVOT) to measure the LAEDD. Results. Age between men and women was not different (p = 0.7050). CMR yielded the following normal ranges for LAEDD: HLA 4.5 ± 0.4 cm for men and 4.2 ± 0.5 for women, VLA 4.5 ± 0.5 cm for men and 4.2 ± 0.4 for women, and LVOT 2.8 ± 0.3 cm for men and 2.8 ± 0.4 for women. LAEDD were significantly larger in HLA and VLA than in LVOT (p 0.0001). There was no significant difference in the measurements between HLA and VLA (p = 0.4617). Gender-related differences for LAEDD were found in HLA (p = 0.0087) and VLA (p = 0.0015) but not in LVOT (p = 0.5281). LAEDD were not found to be age-related (p 0.0994). Conclusions. LAEDD differ significantly according to the image plane. We provide reference values for CMR using prospective triggering in the evaluation of left atrial diameters to identify patients with enlarged left atria and for followup studies.