Background Although left atrial (LA) size is known to be related to the recurrence of atrial fibrillation (AF) after radiofrequency catheter ablation (RFCA), the morphological changes of LA based on its embryological origins have not yet been reported.
Methods and Results We analyzed the 3D CT images of LA in 40 patients with AF (31 males, 55.8±11.2 years old, 18 Paroxysmal AF (PAF) and 22 Persistent AF (PeAF)) who underwent RFCA. Each of LA images was divided into venous atrium (VA), anterior LA (ALA), and LA appendage (LAA), and the volume of each of these divisions was calculated. The volumes of right and left side antrum were also quantified, and the lengths of both antral circumferences, roof, left lateral isthmus (LLI), posterior inferior wall, and right and left anterior wall were measured. Results: 1. Although LA volumes (151.5±44.7mL vs. 103.8±32.5mL, p<0.01) were significantly bigger in patients with PeAF, the proportions of VA (31.7±29.7% vs. 30.2±37.2%, p=NS), ALA (58.7±70.0% vs. 59.9±78.5%, p=NS), LAA (9.7±10.4% vs. 9.9±11.7%, p=NS), and left side antrum (9.7±10.0% vs. 8.9±15.4%, p=NS) were similar between PeAF and PAF. However, the right antral volumes were not significantly enlarged (10.3±4.5mL vs. 8.9±3.9mL, p=NS), and these volumes as a proportion of the total LA volume was reduced in PeAF (6.8±10.0% vs. 8.5±12.0%, p<0.01). 2. The lengths of roof (p<0.03), posterior inferior line (p<0.01), LLI (p<0.02), bilateral anterior lines (p<0.01), left antral circumferences (p<0.01), and right antral circumferences (p<0.02) were all significantly longer in patients with PeAF than in those with PAF. 3. The patients with recurrence 3 months after RFCA had LA with longer LLI (32.75±6.24mm vs. 36.42±4.13mm, p<0.04) and larger anterior LA volume (ALA+LAA; 65.67±7.54% vs. 70.69±5.03%, p<0.03) than those without recurrence.
Conclusion The LA of PeAF showed simultaneous enlargements of VA, ALA, LAA, and left side antrum, but the right side antrum did not increase in volume as compared with that of PAF. The enlargement of anterior part of LA and long LLI were more significant in patients with recurrence after RFCA than those remained in sinus rhythm.
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