[Magnesium protects myocardium during electric cardioversion but does not increase effectiveness]

Transient elevation of serum enzyme level and abnormalities of repolarization following electrical cardioversion (EC) are usually observed. We aimed to alleviate these alterations by pretreatment with magnesium sulfate (MgSO4). The study group consists of 100 patients (aged 19-65 years) who had EC (300 W/sec) for chronic atrial fibrillation after mitral and/or aortic valve surgery. They were randomly divided into two sub groups: 50 patients in whom MgSO4 was administered intravenously (dose 100 m/kg b.w.) and 50 control subjects. Total serum magnesium level and CKMB level were recorded before and 8 hours after EC. Recovery to sinus rhythm, QTc interval, segment shifts were recorded immediately before and after EC. Results (mean +/- SE): [table: see text] Our results suggest that MgSO4 administered before EC has a significant cardioprotective effect and reduces abnormalities of repolarization.