Novel computed tomography indexes of left atrial appendage stasis

Contrast enhanced multi-detector computed tomography (MDCT) may detect left atrial appendage (LAA) thrombus; however, its ability to qualify LAA stasis has not been studied. We sought to identify MDCT derived LAA radiographic parameters which could qualify LAA stasis as defined by established transesophageal echocardiography (TEE) parameters. Pre-procedural MDCT followed by TEE (median procedural time difference of 11 days) from 45 patients who underwent ablation for atrial fibrillation were analyzed retrospectively. Contrast enhanced, non-gated, helical MDCT (64 detector row) was performed according to the institutional protocol. Using a combination of parametric and nonparametric tests, the mean attenuation and heterogeneity parameters of LAA attenuation were correlated with the presence of spontaneous echocardiographic contrast and Doppler derived LAA emptying velocity on TEE. If significant correlation is observed, a receiver operating curve analysis will be performed. The baseline characteristics of the studied population were; age, 62 ± 11; CHADS2 score, 2.0 ± 1.2; heart rate, 79 ± 10 bpm; left ventricular ejection fraction, 49 ± 14%. SEC was seen on TEE in 19 patients; ten with mild, eight with moderate, and one had severe SEC. No patients had LAA thrombus. Compared with the group without SEC, those with SEC had significantly increased coefficient of variation (0.19 vs. 0.14, p = 0.014) and range to mean ratio (1.04 vs. 0.73, p = 0.011). There was no significant correlation between mean LAA attenuation and LAA emptying velocity. However, the range, range to mean ratio, standard deviation and coefficient of variation of LAA attenuation had a significantly negative correlation with LAA emptying velocity (r = -0.486, r = -0.497, r = -0.434, r = -0.466, respectively, all p < 0.05). On receiver operating curve analysis, each of the heterogeneity parameters significantly discriminated LAA emptying velocities ≤30 cm/s, with areas under the curve of 0.88, 0.83, 0.81 and 0.76 respectively. In patients with atrial fibrillation, increased contrast heterogeneity within the LAA on MDCT correlated with decreased LAA emptying velocity on TEE. Contrast enhanced MDCT provides an adjunctive, noninvasive technique for Qualification of LAA stasis.