In this study, adeno-associated virus subtype 9 (AAV9)-transferred PIASy short hairpin RNAs (shRNAs) were used in in vivo myocardial I/R rat and in vitro hypoxia/reoxygenation (H/R) models in isolated adult rat cardiomyocytes and human embryonic kidney 293 T (HEK293T) cells transfected with SUMO machinery, to examine whether enhanced PIASy activity-mediated Cav-3 SUMOylation after myocardial I/R contributes to plasma membrane Nav1.5 downregulation and ventricular arrhythmias. The gene discussed is SCN5A; the disease is Ventricular arrhythmia.