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Prolonged QT Interval due to Medication
Aka: Prolonged QT Interval due to Medication, Drug-Induced Torsades de Pointes
- See Also
- Prolonged QT
- Torsades de Pointes
- Risk Factors: Medication-Induced Torsades de Pointes
- Female gender
- Elderly
- Hypokalemia
- Hypocalcemia
- Severe Hypomagnesemia
- Hepatic or renal dysfunction
- Bradycardia
- Atrial Fibrillation Cardioversion recently
- Congestive Heart Failure
- Left Ventricular Hypertrophy
- Myocardial Infarction
- Concurrent Digoxin use
- Concurrent Diuretic use
- Baseline QT Prolongation or subclinical Long QT
- Multiple concurrent agents that prolong QT
- Rapid infusion of agents known to cause Prolonged QT
- Higher doses of predisposing drug raise risk
- Causes: Cardiovascular agents
- Diuretics
- Vasodilators
- Antiarrhythmics (all are considered higher risk)
- Amiodarone
- Procainamide
- Dofetilide (Tikosyn)
- Sotalol (Betapace)
- Quinidine
- Causes: Antiemetics
- Phenothiazines
- Ondansetron (Zofran)
- Dolasetron (Anzemet)
- Granisetron
- If QTc is already prolonged, Metoclopramide (Reglan), Palonosetron (Aloxi), Prochlorperazine are safe alternatives
- 5HT3 agents are unlikely to cause harm (even at highest dose, Ondansetron prolongs QTc only 20 ms)
- Freedman (2014) Ann Emerg Med 64(1): 19-25 +PMID:24314899 [PubMed]
- Moffett (2016) Acad Emerg Med 23(1): 102-5 +PMID: 26720490 [PubMed]
- Causes: Psychiatric Agents
- Antipsychotics
- Highest risk: Thioridazine, pimozide, Haloperidol, chlorperazine
- Some risk: Geodon, Fanapt, Invega, Saphris, Seroquel
- Consider lower risk agents: Abilify, Latuda, Zyprexa
- Antidepressants
- Highest risk
- Tricyclic Antidepressants (Amitriptyline, Desipramine)
- Trazodone
- Fluoxetine (Prozac)
- Citalopram and Escitalopram (especially in combination with Cytochrome P450 2C19)
- Limit Citalopram (Celexa) to 20-40 mg/day
- Limit Escitalopram (Lexapro) to 10-20 mg/day
- Some risk
- Venlafaxine
- SSRIs in general
- Consider lower risk agents: Bupropion, Duloxetine, Mirtazapine
- Causes: Antimicrobials
- Fluoroquinolones
- Class effect (includes Levofloxacin, Moxifloxacin)
- Consider lower risk agent: Ciprofloxacin
- Macrolides
- Includes Clarithromycin, Erythromycin, Azithromycin
- Three fold increased risk of Sudden Cardiac Death while on Azithromycin
- Ray (2013) N Engl J Med 366(20): 1881-90 [PubMed]
- Antifungals
- Fluconazole
- Ketoconazole
- Itraconazole
- Other agents
- Protease Inhibitors
- Quinine
- Pentamidine
- Causes: Miscellaneous Agents
- Antihistamines and other Anticholinergics
- Hydroxyzine (associated more with QT Prolongation than other Antihistamines)
- Diphenhydramine
- Opioids
- Highest risk agents: Methadone, Buprenorphine, Oxycodone
- Consider lower risk agents: Morphine
- Sympathomimetics
- Amphetamines
- Decongestants
- Seratonin Agonists
- Sumatriptan (Imitrex)
- Zolmitriptan (Zomig)
- Causes: Medications that more commonly cause Torsades
- Bepridil
- Disopyramide
- Dofetilide
- Ibutilide
- Procainamide
- Methadone
- Quinidine
- Sotalol
- Causes: Medications that less frequently cause Torsades
- Amiodarone
- Arsenic trioxide
- Chlorpromazine
- Cisapride
- Clarithromycin
- Domperidone
- Droperidol
- Erythromycin
- Halofantrine
- Haloperidol
- Lidoflazine
- Mesoridazine
- Pentamidine
- Pimozide
- Sparfloxacin
- Thioridazine
- Labs
- Basic metabolic panel
- Serum Magnesium
- Imaging
- Consider Echocardiogram
- Excludes structural heart disease
- Management
- Stop offending agent
- Correct electrolyte abnormalities, considering 5H5T causes (esp. Potassium abnormalities)
- Consider Magnesium Sulfate 1-2 grams prophylactically
- Indications to consider telemetry admission
- QTc Interval >500 ms
- QTc Interval increased 60 ms over baseline
- T-Wave alternans
- Atrioventricular Block
- QRS Widening
- Syncope
- Manage Torsades de Pointes
- See Torsades de Pointes
- Electrical cardioversion (Nonsynchronized)
- Magnesium Sulfate 2 grams
- May be repeated in 5-15 minutes
- May be continued as infusion Magnesium 3 to 20 mg/min IV for Prolonged QTc
- Overdrive pacing
- Set at rate >100 bpm
- Other measures
- Isoproterenol has been used historically and is generally not recommended
- Dosing was bolus and infusion with titrate to Heart Rate >100 bpm
- References
- Glauser and Peters (2016) Crit Dec Emerg Med 30(4): 17-27
- Drew (2017) J Am Coll Cardiol 55(9): 934-47 +PMID:20185054 [PubMed]
- Roden (2004) N Engl J Med 350:1013-22 [PubMed]
- Wexler (2011) Am Fam Physician 84(1): 63-9 [PubMed]