In this study, we examined the effect of acute upregulation of SERCA2a on myocyte Ca cycling and arrhythmia susceptibility in the setting of hyperactive RyR2s using CASQ2 KO mice with doxycycline inducible overexpression of cardiac SERCA2a (KO-TG/DOX+). The gene discussed is CASQ2; the disease is Arrhythmia.