RYR2 and atrial fibrillation: In non-AF RAA, there was a mean of 42.44 ± 2.28% of RyR2 clusters aligned with the z-disk, which was not significantly altered in either of the AF patient groups (paroxysmal AF: 45.89 ± 2.45% and persistent AF: 46.60 ± 2.24%; Figure 4D).