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. Here, CAMK2G is linked to cardiac arrhythmia.