Also, it is not clear if magnesium supplementation is useful for these patients, or it is useful only in hypomagnesemia patients. Hypophosphatemia and its consequences are less investigated in patients after cardiac surgery. Common complications after cardiac surgery are cardiac and respiratory failure, and they are also among the clinical manifestations of hypophosphatemia. Hypophosphatemia could be the cause of prolonged artificial lung ventilation and myocardial dysfunction; also, it may have influence on the incidence of arrhythmias. Anyway, there are no data confirming the arrhythmogenic effect of changes in serum phosphate level.