Pro-arrhythmogenic effects of heterogeneous tissue curvature ― A suggestion for role of left atrial appendage in atrial fibrillation ―

Background: The arrhythmogenic role of atrial complex morphology has not yet been clearly elucidated. We hypothesized that bumpy tissue geometry can induce action potential duration (APD) dispersion and wavebreak in atrial fibrillation (AF). Methods and Results: We simulated 2D-bumpy atrial model by varying the degree of bumpiness, and 3D-left atrial (LA) models integrated by LA computed tomographic (CT) images taken from 14 patients with persistent AF. We also analyzed wave-dynamic parameters with bipolar electrograms during AF and compared them with LA-CT geometry in 30 patients with persistent AF. In 2D-bumpy model, APD dispersion increased (p<0.001) and wavebreak occurred spontaneously when the surface bumpiness was higher, showing phase transition-like behavior (p<0.001). Bumpiness gradient 2D-model showed that spiral wave drifted in the direction of higher bumpiness, and phase singularity (PS) points were mostly located in areas with higher bumpiness. In 3D-LA model, PS density was higher in LA appendage (LAA) compared to other LA parts (p<0.05). In 30 persistent AF patients, the surface bumpiness of LAA was 5.8-times that of other LA parts (p<0.001), and exceeded critical bumpiness to induce wavebreak. Wave dynamics complexity parameters were consistently dominant in LAA (p<0.001). Conclusion: The bumpy tissue geometry promotes APD dispersion, wavebreak, and spiral wave drift in in silico human atrial tissue, and corresponds to clinical electro-anatomical maps.