Aim: To define the incidence, presentation, and outcomes of drug-induced Torsades de Pointes (TdP) with intravenous (IV) amiodarone.
Methods: From January 2014 to August 2016 a total of 268 patients received IV amiodarone, 142 for ventricular tachycardia, 104 for atrial flutter/fibrillation, and 22 for incessant atrial tachycardia. A uniform dosing of amiodarone to yield 1gm/day was used in all patients.
Results: Four of the 268 patients (M:F 1:3) with mean age of 51.25+9.17years developed pause dependent TdP degenerating to VF, after a mean dose of 690+176.63mg, infused over 12+5.88h. The QTc that was 505+9.02ms at the time of TdP normalized to 433.75+6.13ms 48-72h after stopping amiodarone. There was no immediate or late mortality, and patients are well at 5-10 months of follow-up. None of the patients tested positive for LQTS genes.
Conclusion: The incidence of drug-induced TdP with IV amiodarone is about 1.5%. Risk factors include female sex, left ventricular dysfunction, electrolyte abnormalities, baseline prolonged QTc, concomitant beta-blocker, and digoxin therapy. Amiodarone induced TdP has favorable prognosis if recognized and treated promptly, and these patients should not receive amiodarone by any route in future.
Keywords: Acquired LQT; Amiodarone; Proarrhythmia; Torsades de pointes.
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