Friday October 17, 2008

Scenario: You have a 88 year old male admitted with COPD exacerbation. Patient's code status is Do Not Resuscitate (DNR) but chemical intervention is granted. Patient went into Atrial fibrillation & Rapid Ventricular Rate (RVR), with heart rate 150-170. Blood pressure is marginal and you want to avoid calcium channel blockers or beta-blockers. Electrolytes drawn 4 hours ago were reported normal. You decide to manage patient with ibutilide. Which other drug you may consider to use prior to or concomittently with Ibutalide.



Answer: Intravenous Magnesium

Ibutilide (Corvert) is indicated for the chemical conversion of atrial fibrillation. It prolongs action potential duration in myocytes and increases both atrial and ventricular refractoriness. Dose is .01 mg/kg (Up to 1mg total) IV over 10 minutes. About 2% of patients may convert into polymorphic ventricular tachycardia (torsade de pointes) and therefore Ibutilide should not be used in patients receiving concomitant drugs which prolong the QT interval. If time and clinical situation permits, some clinicians preload patients with intravenous magnesium (2-4 grams) prior to infusing ibutilide as a preventative measure for torsade de pointes (TdP).

Interestingly, one study also showed that prophylactic magnesium improve the antiarrhythmic efficacy of ibutilide as demonstrated by an increase in the rate of successful chemical conversion and reduction in the need for direct current cardioversion.


References: Click to get article

1. Intravenous Magnesium Sulfate Enhances the Ability of Intravenous Ibutilide to Successfully Convert Atrial Fibrillation or Flutter - Pacing and Clinical Electrophysiology, Volume 30, Number 11, November 2007 , pp. 1331-1335(5)

2. Cost Effectiveness of Ibutilide With Prophylactic Magnesium in the Treatment of Atrial Fibrillation - PharmacoEconomics, Volume (Year): 22 (2004)Issue: 13, Pages: 877-883