RYR2 and Arrhythmia: Conventional Antiarrhythmics Class I-IV, Late INa Inhibitors, IKs Enhancers, RyR2 Stabilizers, Gap Junction Modulators, Atrial-Selective Antiarrhythmics, and Stable Gastric Pentadecapeptide BPC 157 as Useful Cytoprotective Therapy in Arrhythmias.