N-(3,5-bis-(di-substituted aminomethyl-4-hydroxy)benzyl aromatic sulfamides and N-(3,5-bis-(di-substituted aminomethyl-4-hydroxy)phenyl aromatic sulfamides compounds, in accordance with the animal tests, are active in the prevention and the treatment of cardiac arrhythmias. These compounds are prepared as corresponding diamines by the condensation of optionally substituted aromatic sulfochlorides with p-hydroxybenzylamine, p-aminophenol, or the like, which followed by the Mannich reaction of the resulted corresponding aromatic sulfamides with formaldehyde and secondary amines; or directly obtained by the reaction of the aromatic sulfamides with 4-amino-2,6-bis-di-subsituted aminomethylphenol. Subsequently, the diamines are reacted with various acids to provide their salts.