Pentafluorosulfany0lphenyl-substituted benzoylguanidines, process for their preparation, theie use as medicament or diagnostic aed, and medicament comprising them Pentafluorosulfany0lphenyl-substituted benzoylguanidines of the formulae I and II ##STR00001## in which R1, R1', R2, R2', R3, R3', R4 and X have the meanings indicated in the claims, are suitable as antiarrhythmic medicaments with a cardioprotective component for the prophylaxis of infarction and treatment of infarction and for the treatment of angina pectoris. They also inhibit preventively the pathophysiological processes associated with the development of ischemia-induced damage, especially in the triggering of ischemia-induced cardiac arrhythmias.