Diagnostic Performance of Left Atrial Diameter Measurement in Computed Tomography to Detect Increased Left Atrial...

The left atrium (LA) is frequently imaged in cardiac computed tomographic (cCT) examinations. The LA volume can be accurately measured with three-dimensional (3D) volumetry but this method is time consuming and thus not routinely used in clinical practice. Accordingly, increased LA size may be overlooked although volume enlargement is associated with adverse cardiovascular events. We evaluated the accuracy of LA diameter measurement in cCT and in transthoracic echocardiography (TTE) in the diagnosis of LA enlargement using 3D cCT as the reference standard.

Altogether, 146 patients with suspected cardiogenic stroke underwent cCT and TTE. LA volume by cCT was determined for all patients. LA diameter was measured in both modalities. Furthermore, 40 healthy controls were analyzed in order to assess the cut-off values for normal LA volume. Diagnostic performance of cCT and conventional TTE diametrical measurements for detecting enlarged LA volume were analyzed and compared using Cohen's kappa (κ).

In controls, the mean LA volume was 59.8±15.3 ml and the mean LA diameter was 30.4±5.0 mm by cCT. The mean value plus twice the standard deviation, which was considered the upper limit, for normal LA volume and diameter were 90.4 ml and 40.4 mm, respectively. Age- and gender-matched patients with stroke had statistically significantly (p<0.001) larger LA volumes (85.5±21.1 vs. 59.8±15.3 ml) and diameters (37.6±5.7 vs. 30.4±5.0 mm) than controls. LA diameter measurement by cCT was more reliable in detecting an LA volume enlargement than the corresponding measurement with TTE (κ=0.489 vs. 0.234; p=0.002).

An enlarged LA diameter measured by cCT was more reliable than TTE at detecting enlarged LA volume.