Medications That Can Prolong the QTc Interval on ECG

Introduction to QT Prolongation

Multiple medication classes can prolong the QTc interval on ECG, including antiarrhythmics, antipsychotics, antibiotics, and other drugs that affect cardiac repolarization, according to the American Heart Association 1, 2, 3

Class IA antiarrhythmics, such as quinidine, procainamide, and disopyramide, can prolong the QTc interval, as recommended by the American College of Cardiology 4, 5
Class III antiarrhythmics, including amiodarone, sotalol, dofetilide, and ibutilide, can also cause QT prolongation, with the American Heart Association recommending close monitoring 1, 6, 7
Dofetilide is associated with significant QT prolongation and requires hospitalization during initiation, as stated by the American College of Cardiology 1, 7
Amiodarone causes marked QT prolongation but has a relatively lower risk of torsades de pointes compared to other antiarrhythmics, according to the American Heart Association 4, 5

Macrolide antibiotics, such as azithromycin, clarithromycin, and erythromycin, can prolong the QTc interval, as reported by the European Respiratory Society 2
Antifungals, including ketoconazole, voriconazole, itraconazole, and fluconazole, can also cause QT prolongation, with the Infectious Diseases Society of America recommending caution 3, 8
Antimalarials, such as chloroquine and hydroxychloroquine, can prolong the QTc interval, as stated by the Centers for Disease Control and Prevention 3, 8
Antitubercular drugs, including bedaquiline, can cause QT prolongation, with the World Health Organization recommending monitoring 2, 3, 8, 9

Patient-specific factors, such as older age, heart disease, bradycardia, electrolyte abnormalities, and genetic predisposition, can increase the risk of QT prolongation, as reported by the American College of Cardiology 3, 4, 5
ECG warning signs, including QTc >500 ms, increase in QTc >60 ms from baseline, T wave abnormalities, bradycardia, and polymorphic ventricular premature beats, can indicate QT prolongation, according to the American Heart Association 4, 5, 8

Baseline ECG is recommended before starting QT-prolonging medications, with the American College of Cardiology suggesting follow-up ECG monitoring 6, 7
Electrolyte monitoring, including potassium and magnesium, is recommended at baseline and periodically, as stated by the American Heart Association 6, 7
Renal function assessment is necessary for medications eliminated renally, such as dofetilide and sotalol, according to the American College of Cardiology 6, 7

Discontinuing the offending drug is recommended if QTc >500 ms or increases >60 ms from baseline, with the American Heart Association suggesting correction of electrolyte abnormalities 2, 9
Avoiding combinations of multiple QT-prolonging drugs and considering alternative medications with lower risk of QT prolongation is recommended, as stated by the American College of Cardiology 4, 5
Continuous ECG monitoring is necessary until QTc returns to baseline after discontinuing the offending drug, according to the American Heart Association 4, 5

The European Heart Journal recommends considering the risk of QT prolongation when metoclopramide is combined with other QT-prolonging medications, as this increases the risk of ventricular arrhythmias and sudden cardiac death 10
The combination of metoclopramide with other QT-prolonging drugs significantly increases the risk of torsades de pointes and should be avoided when possible, according to the European Heart Journal 10

Before starting metoclopramide, the European Heart Journal suggests reviewing current medications for potential QT-prolonging drug interactions 10
During metoclopramide treatment, the European Heart Journal recommends monitoring for potential QT-prolonging drug interactions 10
The European Heart Journal advises against overlooking drug interactions that can increase metoclopramide levels or independently prolong QT interval 10