Arrhythmia

Magnesium deficiency. Role in arrhythmias complicating acute myocardial infarction?

Bigg RP; Chia R

Med J Aust 1981 Apr 4;1(7):346-8

Magnesium deficiency is likely to occur in certain patients prone to developing acute myocardial infarction, such as hypertensive patients being treated with diuretics, alcoholics, diabetics and patients with ischaemic cardiomyopathy taking diuretics and digitalis. Magnesium deficiency commonly accompanies potassium deficiency, can also cause it, and can prevent correction of potassium deficiency if potassium supplements alone are used. The results of analysis of plasma magnesium and potassium levels in 25 patients presenting with acute myocardial infarction are presented. Three patients were hypomagnesaemic and all exhibited serious ventricular arrhythmias (two patients exhibited early ventricular fibrillation and the third exhibited ventricular trigeminy and multifocal ventricular ectopy). Two of the three hypomagnesaemic patients were hypokalaemic. Two other patients in the series exhibited ventricular tachycardia and both were hypokalaemic. Magnesium therapy should be considered in hypokalaemic patients during the early stages of acute myocardial infarction, as the body distribution kinetics of magnesium and potassium are interlinked and magnesium deficiency may be the crucial factor in hypokalaemia-associated arrhythmias. In addition, consideration should be given to magnesium supplementation in patients prone to acute myocardial infarction if there is a likelihood of magnesium deficiency developing, as magnesium-deficient patients may be more susceptible to developing potentially fatal ventricular tachyarrhythmias during the early stages of infarction.