Assessment of left atrial volume and function in patients with permanent atrial fibrillation: comparison of cardiac magnetic resonance imaging, 320-slice multi-detector computed tomography, and transthoracic echocardiography.

Aims: Atrial fibrillation (AF) is a common cardiac arrhythmia that is associated with substantial morbidity and mortality. AF is associated with enlargement of the left atrium (LA), and the LA volume has important prognostic implications for the disease. The objective of the study was to determine how measurements of LA volume and function obtained by transthoracic echocardiography (TTE), cardiac magnetic resonance (CMR), and 320-slice multi-detector computed tomography (MDCT) correlate in patients with permanent AF.
Methods and Results: Thirty-four patients with permanent AF participated in the study. TTE, CMR, and 320-slice MDCT imaging procedures were performed within 7 ± 4 days. 320-slice MDCT overestimated maximal LA volume (LAmax) and minimal LA volume (LAmin) compared with CMR (LAmax: 80 vs. 73 mL/m(2), P = 0.0017; LAmin: 69 vs. 64 mL/m(2), P = 0.0217), whereas TTE underestimated these parameters compared with CMR (LAmax: 60 vs. 73 mL/m(2), P < 0.0001; LAmin: 50 vs. 64 mL/m(2), P < 0.0001), and also compared with MDCT (LAmax: 60 vs. 80 mL/m(2), P < 0.0001; LAmin: 50 vs. 69 mL/m(2), P < 0.0001). Measurements of LA volumes by MDCT and CMR closely correlated, and both MDCT and CMR had excellent intra- and inter-observer agreement with correlation coefficients of >0.90. The correlation between TTE-derived measurements and CMR/MDCT was fair to moderate. Intra- and inter-observer agreement for LA volume measurements by TTE were inferior to CMR and MDCT.
Conclusion: Measurements of LA volumes by CMR and 320-slice MDCT correlate closely in patients with permanent AF, and both modalities improve the reproducibility of measurements of LA volumes and function compared with 2D TTE.