Oral magnesium reduces ventricular ectopy in digitalised patients with chronic atrial fibrillation
We have examined the effects of magnesium replacement therapy upon post-exercise heart rate and incidence of ventricular premature beats (VPB) in digitalised patients with AF. In 11 such patients, all of whom had serum magnesium concentrations of less than 0.85 mmol/l, treatment with magnesium glycerophosphate was associated with a significant reduction in number of VPBs (982 v. 416 VPB/24 h). Five patients had a high prevalence of ventricular ectopy (>300 VPB/24 h) and these subjects showed particularly marked decreases in VPBs during magnesium treatment (1998 v. 690 VPB/24 h). Three patients had slightly increased QTc intervals but these did not change during magnesium replacement. No significant changes were seen in the mean post-exercise heart rate although 2 subjects did show falls of 25% of more during magnesium replacement.
We conclude that treatment with magnesium glycerophosphate may be associated with a decreased prevalence of ventricular ectopy in some digitalised patients with chronic AF and mild-moderate hypomagnesaemia.
Key wordsmagnesium ventral ectopy atrial fibrillation digitalised patients
Unable to display preview. Download preview PDF.
- 1.Camm AJ, Evans KE, Ward DE, Martin A (1980) The rhythm of the heart in elderly active subjects. Am Heart J 99: 598–603Google Scholar
- 2.Nanji AA (1983) Drug-induced electrolyte disorders. Drug Intell Clin Pharm 17: 175–185Google Scholar
- 3.Martin BJ, Milligan K (1987) Diuretic-associated hypomagnesaemia in the elderly. Arch Int Med 147: 1768–1771Google Scholar
- 4.Kupfer S, Kosovsky JD (1965) Effects of cardiac glycosides on renal tubular transport of calcium, magnesium, inorganic phosphate and glucose in the dog. J Clin Invest 44: 1132–1142Google Scholar
- 5.DeCarli C, Sprouse G, LaRosa JC (1986) Serum magnesium levels in symptomatic atrial fibrillation and their relation to rhythm control by intravenous digoxin. Am J Cardiol 57: 956–959Google Scholar
- 6.Elin RJ (1987) Assessment of magnesium status. Clin Chem 33: 1965–1970Google Scholar
- 7.Sheehan J, White A (1982) Diuretic associated hypomagnesaemia. Br Med J 285: 1157–1159Google Scholar
- 8.Roden DM, Iansmith DHS (1987) Effects of low potassium or magnesium concentrations on isolated cardiac tissue. Am J Med 82 [Suppl 3A]: 18–23Google Scholar
- 9.Seller RH, Cangiano J, Kim KE, Mendelssohn S, Brest AN, Schwartz C (1970) Digitalis toxicity and hypomagnesaemia. Am Heart J 79: 57–68Google Scholar
- 10.Lewis RV, McDevitt DG (1988) The relative effects of digoxin and diltiazem upon ventricular ectopic activity in patients with chronic atrial fibrillation. Br J Clin Pharmacol 26: 327–329Google Scholar
- 11.Cleland JGF, Dargie HJ, Ford I (1987) Mortality in heart failure: clinical variables of prognostic value. Br Heart J 58: 572–582Google Scholar
- 12.Rapeport N, Schamroth L (1985) A study of ventricular ectopy during atrial fibrillation. Heart Lung 14: 191–192Google Scholar
- 13.Charbon GA (1987) Pitfalls in a study of magnesium replacement. Magnesium 6: 281–283Google Scholar
- 14.Dyckner T, Wester PO (1979) Ventricular extrasystoles and intracellular electrolytes before and after potassium and magnesium infusions in patients on diuretic treatment. Am Heart J 97: 12–18Google Scholar
- 15.Morganroth JL, Michelson EL, Horowitz LN, Josephson ME, Pearlman AS, Bruce Dunkman W (1978) Limitations of routine long-term electrocardiographic monitoring to assess ventricular ectopic frequency. Circulation 58: 408–414Google Scholar
- 16.Iseri LT, French JH (1984) Magnesium: Nature's physiologic calciu blocker. Am Heart J 108: 188–193Google Scholar
- 17.Ramsay LE (1986) Diuretic drugs. In: Dukes MNG (ed) Side effects of drugs annual 10. Elsevier, Amsterdam, pp 185–198Google Scholar