Medications That Cause Long QT Syndrome

High-Risk Medications

• The European Society of Cardiology recommends that antiarrhythmic drugs, such as disopyramide, dofetilide, ibutilide, procainamide, quinidine, sotalol, and ajmaline, require hospitalization for monitoring during initiation due to frequent QT prolongation 1
• The European Heart Association notes that these medications cause QT prolongation in 1-10% of patients and carry the highest risk for torsades de pointes (TdP) among all drug classes 1, 2

Moderate-Risk Cardiovascular Medications

• The American Heart Association states that amiodarone paradoxically has a surprisingly low incidence of TdP despite causing QT prolongation, and may even be effective in patients with previous drug-induced TdP 1, 3
• The European Society of Cardiology recommends that bepridil, a calcium channel blocker, be used with caution due to its association with polymorphic ventricular arrhythmias 3

Antibiotic-Related LQTS

• The Infectious Diseases Society of America notes that macrolides, such as erythromycin, clarithromycin, and azithromycin, carry the greatest overall risk for QT prolongation and TdP among commonly used antibiotics 4
• The European Society of Clinical Microbiology and Infectious Diseases states that fluoroquinolones, such as sparfloxacin, levofloxacin, and moxifloxacin, also pose a risk for QT prolongation and TdP 1, 2, 4

Antipsychotic Medications

• The American Psychiatric Association notes that typical antipsychotics, such as thioridazine and haloperidol, cause QT prolongation and increase the risk of sudden cardiac death 1, 3
• The National Institute of Mental Health states that atypical antipsychotics, such as quetiapine and ziprasidone, also pose a risk for QT prolongation, although to a lesser extent 5

Opioid Dependence Agents

• The American Society of Addiction Medicine notes that methadone causes pronounced QT prolongation and has been associated with several reported cases of TdP 1, 2, 5

Antihistamines

• The American Academy of Allergy, Asthma, and Immunology states that certain antihistamines, such as terfenadine and astemizole, have been withdrawn from the market due to their association with QT prolongation and TdP 3, 6

Major Risk Factors for Drug-Induced TdP

• The European Society of Cardiology notes that female gender, hypokalemia, hypomagnesemia, bradycardia, and recent conversion from atrial fibrillation are major risk factors for drug-induced TdP 1, 7, 5

Critical Management Principles

• The American Heart Association recommends that removal of the offending agent is indicated in patients with drug-induced LQTS (Class I recommendation, Level of Evidence A) 1, 7
• The European Society of Cardiology states that intravenous magnesium can suppress episodes of TdP without necessarily shortening QT, even when serum magnesium is normal 1

Monitoring Recommendations

• The American College of Cardiology recommends that patients requiring QT-prolonging medications undergo detailed cardiac history, review of complete medication list, baseline electrolyte checks, and baseline ECG to measure QTc interval 4
• The European Society of Cardiology notes that an up-to-date list of QT-prolonging drugs is maintained at www.torsades.org and www.qtdrugs.org 1, 7