[Medicamentous anti-arrhythmia therapy. Is oral adjuvant therapy with electrolytes of value?]

Low serum concentrations of potassium and magnesium are proarrhythmic factors that are well established. Atrial and ventricular fibrillation are facilitated at low serum levels of these electrolytes. Loss of potassium and magnesium might be caused by diuretic therapy, gastrointestinal loss, drugs, and alcohol abuse. However, serum levels are not representative of total body content of potassium and magnesium, hence, adjuvant therapy might be indicated also in the presence of normal serum levels. This is especially true during the initial phase of antiarrhythmic therapy, which is accompanied by proarrhythmia in a significant number of cases. Patients with heart failure should routinely receive adjuvant electrolyte substitution, if renal function is not impaired. In the experimental model magnesium successfully prevented early afterdepolarizations caused by hypokalemia and antiarrhythmic drugs. In the clinical setting high dose magnesium abolished torsade-de-pointes tachycardias caused by antiarrhythmic drugs. Unfortunately, controlled studies are not available for low dose electrolyte therapy adjuvant to antiarrhythmic drug medication.