We accordingly assessed for the first time the effects of acute pharmacological inhibition of CaMKII with KN-93, a direct inhibitor of CaMKII (Fleming et al. 1998) in establishing a causal relationship between EADs and arrhythmic substrate in the initiation of arrhythmias at the whole heart level for the first time in any cardiac preparation. The gene discussed is CAMK2G; the disease is Arrhythmia.