Abstract
BACKGROUND: It is recognized that one of the causes of atrial fibrillation (AF) is pathological degeneration of the left atrium (LA). However, prospective study that elucidated the relationship between the incidence of persistent AF and pathological degeneration has not been performed. The purpose of this study was to elucidate the usefulness of integrated backscatter (IBS) values for the prediction of progression from paroxysmal AF (PAF) to persistent AF. METHODS: We measured IBS values of the entire LA wall at 5 mm intervals (except the posterior wall) in 27 patients with paroxysmal AF and evaluated progression to persistent AF for three years. IBS values were acquired with transesophageal echocardiography (TEE) using a 4-7 MHz transducer. IBS values were calculated as the average power of the backscattered signal from regions of interest (ROI). Each IBS value was color-coded to construct three dimensional maps. RESULTS: Average IBS values of total voxels in color-coded maps in the persistent AF group were significantly greater than those in the non-persistent AF group (25.8 ± 5.0 dB vs. 17.4 ± 10.2 dB, p = 0.047), whereas there was no significant difference in LA diameter between the persistent AF and the non-persistent AF group. There was significant difference in persistent AF-free survival after the baseline measurements in the subjects stratified by IBS value (< 20 dB versus ≥ 20 dB) (univariate Cox regression analysis: hazard ratio: 8.74, p =0.046). CONCLUSION: Using IBS values measured by TEE, we can identify an increase in atrial degeneration that may predict the occurrence of persistent AF before LA dilation.