Intravenous magnesium sulfate enhances the ability of intravenous ibutilide to successfully convert atrial fibrillation or flutter.
BACKGROUND
A previous randomized trial found that adjunctive use of intravenous magnesium (a total of 4 grams) can attenuate the corrected QT interval (QTc) prolongation associated with ibutilide, but its impact on ibutilide efficacy has not been elucidated.


METHODS
This was a cohort evaluation of 229 consecutive patients who received ibutilide in the presence or absence of intravenous magnesium. Multivariate logistic regression analysis was used to determine the impact of magnesium on ibutilide efficacy as well as the impact of magnesium dosing intensity on ibutilide efficacy.


RESULTS
The overall chemical conversion rate with ibutilide in the presence or absence of magnesium was 59.8%. The concurrent administration of magnesium (n = 141) was associated with a 78% increased odds of successful chemical conversion (adjusted odds ratio, AOR; 1.78 [95% confidence intervals,CI 1.02-3.09]) compared to those who did not receive magnesium (n = 88). Magnesium dosing intensity appeared to be an important determinant of ibutilide efficacy, with the 4 grams dose associated with a threefold increase in the odds of successful chemical conversion (AOR; 2.98 [95% CI 1.46-6.11). The 1 to 3 grams subgroup was associated with only a trend toward an improvement. There was only one case of Torsade de Pointes (TdP) which occurred in the no adjunctive magnesium group.


CONCLUSIONS
Concurrent use of magnesium enhanced the ability of ibutilide to successfully convert atrial fibrillation (AF) or flutter (AFl). The 4 grams magnesium dose appeared to provide the greatest benefit.
Tercius
Alix J
AJ
University of Connecticut Schools of Medicine, Farmington, CT, USA.
Kluger
Jeffrey
J
Coleman
Craig I
CI
White
C Michael
CM
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy*; D001282:Atrial Flutter / Q000175:diagnosis / Q000188:drug therapy*; D015331:Cohort Studies; D004359:Drug Therapy, Combination; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008278:Magnesium Sulfate / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D013449:Sulfonamides / Q000008:administration & dosage*; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D013449:Sulfonamides; C067192:ibutilide; D008278:Magnesium Sulfate