Magnesium Therapy for Acute Management of Rapid Af

1. CASE REPORTDr. Amr EL-SaidProfessor Of Anaesthesia & Intensive Care MedicineFaculty of Medicine – Ain Shams University

2. 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.

3. Patient was haemodynamically stable. • Follow up lab investigations including cardiac enzymes were within normal limits. • Patient was discharged from ICU following day.

4. 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.

6. DC cardioversion. After three successive electrical shocks to heart with escalating levels of energy; cardioversionwas unsuccessful. • Drug treatment. Loading dose of cordarone 300 mg over one hour; tachycardia persisted. • Magnesium sulfateinfusion: 1gm/hour. • After 6 hours, sinus rhythm was restored. • Magnesiuminfusion was discontinued following day at 10:30 am.

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

8. Lone Atrial Fibrillationis 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.

9. 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. • Mgdeficiency also leads to leakage of primarily extracellular cationsNaand Ca into cells and primarily intracellular cationsKand Mgout cells. • Mg is antioxidant and Mg deficiency allows accelerated free radical damage to cell membranes. • AgusZS.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.

10. 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. Magnesiumefficacy in magnesium deficient and non-deficient patients with rapidventricular 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.

11. 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 Mggroup and 56% in control group. • Time to response (in hours) was significantly shorter in Mg group than in control group. • Mgadministration was also more effective than control treatments in restoration of sinus rhythm. • Risk of major adverse effect in Mggroup was similar to that in placebo group. • Mg deficiency was in as many as 50% of patients presenting with AF. • OnalanO, 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 JCardiol. 2007;99:1726–1732.

12. 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 Mghas 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.