Congestive heart failure and ventricular arrhythmias in relation to serum magnesium

Abstract

Congestive Heart Failure (CHF) is associated with biochemical evidence of electrolyte imbalance including magnesium deficit, which may increase myocardial electrical instability, risk of malignant arrhythmias and sudden death. The aim of this study was to determine serum magnesium concentration in 45 patients (Group I; 24 male, 21 female; the average age 49.7 years) with CHF, New York Heart Association (NYHA) Class II, III who were treated with lisinopril [Angiotensin-Converting Enzyme Inhibitor (ACEI)], frusemide (diuretic) and digoxin. All patients were subjected to resting 12-lead electrocardiography (ECG) and ventricular arrhythmias were analysed in relation to serum magnesium concentration at baseline and at end of the fourth week of treatment. Control group (Group II; 24 male, 21 female; the average age 49.3 years) were matched with Group I. Serum magnesium was determined by Atomic Absorption Spectrophotometer (AAS). Statistical analysis was with Student's t-test. It was observed that 6 (13.3%) CHF patients had ventricular arrhythmias at the commencement of the study. This number increased to 17 (37.8%) by the end of the fourth week of treatment. At four weeks, there was significant difference in serum magnesium between CHF patients without arrhythmias (0.69 +/- 0.11 mmol x L(-1)) and those with arrhythmias (0.50 +/- 0.01 mmol x L(-1)), P < 0.0001. Results obtained suggest that CHF patients having hypomagnesemia had higher prevalence of ventricular arrhythmias. It should be stressed, however, that 24 hour ECG monitoring and classification of ventricular arrhythmias according to Lown may give a more accurate picture. Nevertheless, routine serum magnesium assays, as part of the electrolyte profile of CHF patients would assist in early prevention and detection of magnesium depletion. This would go a long way to reduce the susceptibility to lethal arrhythmias and sudden death.