Isolated hearts from Casq2-null mice also experienced diastolic subthreshold spontaneous Ca elevations (SCaEs) and delayed afterdepolarizations (DADs) when AF was not reached, but R-propafenone (RyR2 and Na+ channel blocker) was shown to prevent AF, DADs, and SCaEs in these mice. This evidence concerns the gene CASQ2 and atrial fibrillation.