CASE REPORTDr. Amr EL-Said

Professor Of Anaesthesia & Intensive Care MedicineFaculty of Medicine – Ain Shams University

Magnesium Therapy for Acute Management of Rapid Af

• 77 years old male patient was admitted to ICU on 14/10/2012 for post-operative care after subtotal gastrectomy with primary anastomosis.

• Past history was unremarkable. • Pre-operative lab investigations were within

normal limits. • Pre-operative echocardiography was quite

normal apart from impaired diastolic function and trivial MR and AR.

• Patient was haemodynamically stable. • Follow up lab investigations including

cardiac enzymes were within normal limits. • Patient was discharged from ICU following

day.

• On 27/10/2012: patient was re-admitted to ICU at 11:00 pm with tachypnea and severe irregular tachycardia but without cardiac decompensation.

• BP was normal and ABG analysis was satisfactory. • ECG revealed AF. • Last lab investigations were within acceptable

levels. • Blood work obtained in ICU were within normal

limits. • Chest X-ray revealed no parenchymal

abnormality.

• DC cardioversion. After three successive electrical shocks to heart with escalating levels of energy; cardioversion was unsuccessful.

• Drug treatment. Loading dose of cordarone 300 mg over one hour; tachycardia persisted.

• Magnesium sulfate infusion: 1gm/hour. • After 6 hours, sinus rhythm was restored. • Magnesium infusion was discontinued

following day at 10:30 am.

• On 29/10/2012: patient was discharged from ICU.

• Lone Atrial Fibrillation is AF without discernible cardiovascular disease.

• AF potentially leads to prolonged hospitalization and significant morbidity, particularly hemodynamic deterioration and thromboembolic events especially stroke.

• AF has been associated with number of diseases primarily involving organs other than heart.

• “Defective Substrate" has become integral to any discussion of cause of LAF.

• Magnesium (Mg) deficiency has emerged as significant player in etiology of LAF.

• Funk M, Richards SB, Desjardins J, Bebon C and Wilcox H. Incidence, timing, symptoms, and risk factors for atrial fibrillation after cardiac surgery. Am J Crit Care 2003; 12: 424–33.

• Burton MA. Magnesium: We Don't Appear to be Getting Enough. Science News Online. August 29, 1998.

• Mg involves maintenance of intracellular environment.• Mg is also required cofactor in various membrane ATP pumps:

Na/K; Ca/Mg; K/H and Na/H pumps. • Channels (such as Ca and Na) and exchangers (such as Na-

Mg, Na-Ca and Na-H). • Mg is Ca channel blocker and Mg deficiency leads to increased

intracellular Ca.• Mg deficiency also results in dysfunction of Na-Mg exchanger,

leading to increased intracellular Na.• Mg deficiency also leads to leakage of primarily extracellular

cations Na and Ca into cells and primarily intracellular cations K and Mg out cells.

• Mg is antioxidant and Mg deficiency allows accelerated free radical damage to cell membranes.

• Agus ZS. Hypomagnesemia. Journal of the American Society of Nephrology. 1999; 10 (7).• Larsen HR. Lone Atrial Fibrillation: Towards A Cure. 2003, pp. 96, 63.• Chambers P. Magnesium and Potassium in Lone Atrial Fibrillation. The Magnesium Web Site. MAGNESIUM ONLINE

LIBRARY. Editor: Paul Mason, February, 2003.

• Major cardiac effects of Mg are prolongation of atrial and AV nodal refractory periods.

• Mg deficiency is relatively common in patients presenting with AF [20% - 53%].

• Mg deficiency and AF are common after cardiac surgery, and prophylactic Mg use has resulted in significant reduction in incidence of post-operative AF.

• Christiansen EH, Frost L, Andreasen F, Mortensen P, Thomsen PE and Pedersen AK. Dose-related cardiac electrophysiological effects of intravenous magnesium. A double-blind placebo-controlled dose response study in patients with paroxysmal supraventricular tachycardia. Europace. 2000; 2: 320–326.

• Eray O, Akca S, Pekdemir M, Eray E, Cete Y and Oktay C. Magnesium efficacy in magnesium deficient and non-deficient patients with rapid ventricular response atrial fibrillation. Eur J Emerg Med. 2000; 7: 287–290.

• Miller S, Crystal E, Garfinkle M, Lau C, Lashevsky I and Connolly SJ. Effects of magnesium on atrial fibrillation after cardiac surgery: a meta-analysis. Heart. 2005; 91: 618–623.

• Randomized controlled trials comparing IV Mg versus placebo or antiarrhythmic agents for acute management of rapid AF.

• Mg was more effective than control treatments with respect to rate control and rhythm control.

• Overall response rate was 86% in Mg group and 56% in control group.

• Time to response (in hours) was significantly shorter in Mg group than in control group.

• Mg administration was also more effective than control treatments in restoration of sinus rhythm.

• Risk of major adverse effect in Mg group was similar to that in placebo group.

• Mg deficiency was in as many as 50% of patients presenting with AF.

• Onalan O, Crystal E, Daoulah A, Lau C, Crystal A and Lashevsky I. Meta-Analysis of Magnesium Therapy for the Acute Management of Rapid Atrial Fibrillation. Am J Cardiol. 2007; 99: 1726–1732.

• Mg can be used safely in most patients in whom other antiarrhythmic drugs are contraindicated or considered harmful.

• Mg has relatively wide toxic/therapeutic window, and most common reported side effects are transient sensation of warmth and flushing.

• IV Mg has rapid action, which may be useful in controlling symptoms.

• Mg is inexpensive, easy to use and titrate, and widely available for immediate use in every clinical unit.

• Delva P. Magnesium and heart failure. Mol Aspects Med. 2003; 24: 79 –105.• Crippa G, Sverzellati E, Giorgi-Pierfranceschi M, Carrara GC. Magnesium and cardiovascular drugs: interactions and

therapeutic role. Ann Ital Med Int. 1999; 14: 40–45.