The significance of the shape of the left atrial roof as a novel index for determining the electrophysiological and structural characteristics in patients with atrial fibrillation.

AIM The silhouette of the left atrial (LA) roof is characterized by the pulmonary veins (PVs) and left atrium, and may include the characteristics of the PV/left atrium arrhythmogenicity in patients with atrial fibrillation (AF). In this study, we examined the hypothesis that the characteristics of the LA roof could help us understand the electrophysiological information of the PVs/left atrium. METHODS AND RESULTS The study population consisted of 153 consecutive patients with AF. The shape of the LA roof was determined by simultaneous right- and left-pulmonary angiography and 64-slice multi-detector-row computed tomography. The silhouette was classified into a deep-V shape (A; n= 35), shallow-V (B; n= 76) shape, and flat or coved shape (C; n= 42) according to the PV/left atrium dominancy. The AF triggers from the PVs (A: 70% vs. B: 57% vs. C: 40%; P= 0.003) became significantly less and those from non-PV sites (A: 6% vs. B: 13% vs. C: 22%; P= 0.043) significantly greater, as the LA shape became flat. Burst-inducible atrial tachyarrhythmias after PV isolation (A: 51% vs. B: 65% vs. C: 79%; P= 0.001) and at the end of the catheter ablation (A: 12% vs. B: 24% vs. C: 36%, P= 0.016) significantly increased, as the LA roof shape became flat. Although the PV diameters did not differ among the three groups, the LA volume (A: 69.5 ± 24.1 vs. B: 85.2 ± 34.9 vs. C: 105.7 ± 45.4 mL; P< 0.001) significantly increased as the LA shape became flat. CONCLUSIONS The shape of the LA roof allowed us to understand the structural and the electrophysiological information of the PVs/left atrium.