Spotting a silent killer
Two patients have acute psychosis. Antipsychotics prolong their QTc intervals, placing them at risk for sudden cardiac death. How would you treat them?
Medications. Antipsychotics, tricyclics, and antihistamines can prolong the interval alone or when combined with drugs that inhibit their metabolism. Concomitant use of agents that inhibit cytochrome P-450 enzyme systems may elevate serum concentrations of the interval-prolonging medication,4 as can decreased CYP 2D6 activity.10 Check plasma drug levels in patients who exhibit side effects.
Also check for congenital long QTc interval, autonomic CNS abnormalities, and overdose of a prescribed psychotropic.
Check ECGs every 2 days for inpatients and at every visit for outpatients taking antipsychotics. Frequent testing is crucial for elderly patients with multiple cardiac risk factors who are taking medications likely to increase the interval. Repeat ECGs if the patient reports lightheadedness or palpitations.
QTc interval prolongation is minimal in healthy young adults taking antipsychotics, so order ECGs only when symptoms arise. A baseline ECG is advisable but not necessary.
Order a cardiology consult and immediate ECG when the QTc interval exceeds 500 msec11 or if the patient exhibits arrhythmia symptoms (palpitation chest pain, dizziness, presyncope, syncope). Work with the cardiologist to manage medication.
Related resources
- University of Arizona Center for Education and Research on Therapeutics. Drugs that prolong the QT interval. https://www.qtdrugs.org/medical-pros/drug-lists/drug-lists.htm
- Glassman AH, Bigger JT Jr. Antipsychotic drugs: prolonged QTc interval, torsade de pointes, and sudden death. Am J Psychiatry 2001;158:1774-82.
Drug brand names
- Atorvastatin • Lipitor
- Benztropine • Cogentin
- Citalopram • Celexa
- Clonazepam • Klonopin
- Divalproex • Depakote
- Donepezil • Aricept
- Esomeprazole • Nexium
- Gabapentin • Neurontin
- Haloperidol • Haldol
- Hydrochlorothiazide • Atacand, others
- Lorazepam • Ativan
- Loxapine • Loxitane
- Olanzapine • Zyprexa
- Quetiapine • Seroquel
- Risperidone • Risperdal
- Thioridazine • Mellaril
- Ziprasidone •Geodon
Disclosure
Dr. Tampi receives research support from the division of state, community, and public health, bureau of health professions, Health Resources and Services Administration, Department of Health and Human Services.
Dr. Ruedrich receives grants from Pfizer Inc. and Eisai Inc., and is a consultant to Abbott Laboratories.
The other authors report no financial relationship with any company whose products are mentioned in this article or with manufacturers of competing products.
