A method and composition is disclosed for reducing the extent of cardiac arrhythmias, both resulting from loss, decrease or interruption to the blood supply such as may happen during a heart attack or during cardiac surgery, in mammals. In particular, the present invention relates to a method of limiting or preventing cardiac cell damage and/or death, and limiting or preventing lethal or non-lethal cardiac arrhythmias, in a human, by administering to the cardiac cells a compound which selectively blocks or partially blocks persistent sodium currents and/or persistent sodium channels of cardiac cells. The composition involves any physiologically acceptable chemical or pharmaceutical composition comprising as its active ingredient a cardiac persistent sodium current and/or persistent sodium channel blocker.
