NEW YORK (Reuters Health) – Cardioversion of atrial fibrillation or flutter to sinus rhythm using ibutilide is more successful and less likely to trigger torsades de pointes when high-dose magnesium sulfate is infused before and immediately after ibutilide administration, Greek cardiologists report.
Dr. Apostolos Christou, of Konstantopoulio General Hospital, Athens, and colleagues point out in a July 23 online issue of the American Journal of Cardiology that torsades de pointes occurs in about 4% of patients treated with ibutilide, because of QT prolongation. While magnesium has been used successfully to treat torsades de pointes, its routine prophylactic use with ibutilide has not yet been established.
To investigate, the researchers studied 476 consecutive patients admitted with recent onset atrial fib of atrial flutter. All received an IV infusion of 1 mg of ibutilide over 10 minutes to convert them to sinus rhythm, with a second infusion if needed. Rather more than half the patients were also given an infusion of 5 g magnesium sulfate over 1 hour before ibutilide administration, followed by another 5-g magnesium infusion for 2 additional hours.
The cardioversion success rate was 76.5% in the magnesium group and 67.3% in the non-magnesium control group (p=0.033), Dr. Christou and colleagues report.
Ventricular tachycardia or torsades de pointes did not occur in the group treated with high-dose magnesium but did in 3.5% of those in the control group.
“The administration of magnesium (despite the high doses used) was well tolerated, with no serious complications or adverse effects,” the authors found. Transient minor symptoms of flushing, tingling, and dizziness were reported by about 14% of the patients.
“Thus,” the investigators conclude, “magnesium supplementation, although not yet established, might convert ibutilide to a much safer agent and could be used as a routine co-therapy in patients receiving ibutilide for cardioversion of short-lasting atrial fibrillation or flutter, probably changing the current policy of close monitoring of these patients.”
Reference:
Effect of High Doses of Magnesium on Converting Ibutilide to a Safe and More Effective Agent
Am J Cardiol 2010.
