RYR2 and Paroxysmal atrial fibrillation: RyR2 density did not significantly differ between the patient groups (non-AF: 163.6 ± 11.6 a.u., paroxysmal AF: 146.9 ± 17.2 a.u. and persistent AF: 149.4 ± 12.9 a.u.; Figure 2E), indicating that RyR2 channel packing is unaltered within clusters in the RAA of AF patients.