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Prolonged QT Interval due to Medication
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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
Diuretic
s
Vasodilators
Antiarrhythmic
s (all are considered higher risk)
Amiodarone
Procainamide
Dofetilide (Tikosyn)
Sotalol
(
Betapace
)
Quinidine
Causes
Antiemetic
s
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
Antipsychotic
s
Highest risk: Thioridazine, pimozide,
Haloperidol
, chlorperazine
Some risk:
Geodon
, Fanapt, Invega, Saphris,
Seroquel
Consider lower risk agents:
Abilify
, Latuda,
Zyprexa
Antidepressant
s
Highest risk
Tricyclic Antidepressant
s (
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
SSRI
s in general
Consider lower risk agents:
Bupropion
,
Duloxetine
,
Mirtazapine
Causes
Antimicrobials
Fluoroquinolone
s
Class effect (includes
Levofloxacin
,
Moxifloxacin
)
Consider lower risk agent:
Ciprofloxacin
Macrolide
s
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]
Antifungal
s
Fluconazole
Ketoconazole
Itraconazole
Other agents
Protease Inhibitor
s
Quinine
Pentamidine
Causes
Miscellaneous Agents
Antihistamine
s and other
Anticholinergic
s
Hydroxyzine
(associated more with
QT Prolongation
than other
Antihistamine
s)
Diphenhydramine
Opioid
s
Highest risk agents:
Methadone
,
Buprenorphine
,
Oxycodone
Consider lower risk agents:
Morphine
Sympathomimetic
s
Amphetamine
s
Decongestant
s
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 QT
c
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]
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