Application of data to the case

Our 88-year-old patient has multiple risk factors for a prolonged QTc, and according to the Tisdale scoring system is at moderate risk (7-10 points). Her risk of developing TdP increases with the addition of IV haloperidol to her regimen.

Because of her increased risk, it is reasonable to consider alternative management. If she can cooperate with PO medications, then olanzapine could be given, which has a lesser effect on the QTc interval. If unable to take oral medications, she could be given haloperidol intramuscularly, which causes less QTc prolongation than the IV formulation. If an antipsychotic is administered, she should receive EKG monitoring.

Given the lack of evidence on the optimal monitoring strategy, a protocol should be utilized that balances the ability to capture a clinically meaningful increase in the QTc with appropriate stewardship of resources. Our practice is to initially monitor the EKG every 3 days in moderate- to high-risk patients with baseline QTc < 500 ms. If the QTc remains below 500 ms over three EKGs, then treatment may continue with EKG monitoring weekly while the patient is hospitalized. If the QTc rises above 500 ms, then a management change would be indicated (either dose reduction or a change of agents). If antipsychotic medications are continued, we check the EKG daily while the QTc is >500 ms until there are three unchanged EKGS, and then consider deescalating monitoring to every 3 days.

Bottom line

Prior to prescribing, perform a baseline EKG and assess the patient’s risk of QTc prolongation. If the patient is at increased risk, avoid prescribing QTc prolonging medications where alternatives exist. If a QTc prolonging medication is used in a patient with a moderate- to high-risk score, check an EKG every 3 days or daily if the QTc increases to > 500 ms.

Ms. Platt is a medical student at the Icahn School of Medicine at Mount Sinai in New York. Mr. Rice is a medical student at the Icahn School of Medicine. Dr. Mirza is assistant clinical professor of psychiatry at the Icahn School of Medicine. Dr. Dunsky is a cardiologist and assistant professor at the Icahn School of Medicine. Dr. Portnoy is a hospitalist and assistant professor at the Icahn School of Medicine.

References

1. Darpö B. Spectrum of drugs prolonging QT interval and the incidence of torsades de pointes. Eur Heart J Supplements. 2001;3(suppl_K):K70-K80. doi: 10.1016/S1520-765X(01)90009-4.

2. Schwartz PJ, Woosley RL. Predicting the unpredictable: Drug-induced QT prolongation and torsades de pointes. J Am Coll Cardiol. 2016;67(13):1639-50. doi: 10.1016/j.jacc.2015.12.063.

3. Rautaharju PM et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram. Part IV: The ST Segment, T and U Waves, and the QT Interval A Scientific Statement From the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society Endorsed by the International Society for Computerized Electrocardiology. J Am Coll Cardiol. 2009 Mar 17;53(11):982-91. doi: 10.1016/j.jacc.2008.12.014.

4. Drew BJ et al. Prevention of torsades de pointes in hospital settings: A scientific statement from the American Heart Association and the American College of Cardiology Foundation. Circulation. 2010;121(8):1047-60. doi: 10.1161/CIRCULATIONAHA.109.192704.

5. Zolezzi M, Cheung L. A literature-based algorithm for the assessment, management, and monitoring of drug-induced QTc prolongation in the psychiatric population. Neuropsychiatr Dis Treat. 2019;15:105-14. doi: 10.2147/NDT.S186474.

6. Tisdale JE et al. Development and validation of a risk score to predict QT interval prolongation in hospitalized patients. Circ Cardiovasc Qual Outcomes. 2013;6(4):479-87. doi: 10.1161/CIRCOUTCOMES.113.000152.

7. Beach SR et al. QT prolongation, torsades de pointes, and psychotropic medications: A 5-year update. Psychosomatics. 2018;59(2):105-22. doi: 10.1016/j.psym.2017.10.009.

Key points

• An increased QTc interval can lead to TdP, ventricular fibrillation and cardiac death.
• The relative risk of each antipsychotic medication should be determined based on available data and the Tisdale scoring system can provide a system to assess a patient’s risk of QTc prolongation.
• Low-risk patients with a baseline QTc <500 ms should receive a baseline EKG and inpatient EKG monitoring weekly while moderate- to high-risk patients should receive EKG monitoring every 3 days.
• A QTc > 500 ms suggests the need for a management change (drug discontinuation, dose reduction, or a switch to another agent). If the antipsychotic is absolutely necessary, perform daily EKG monitoring until there are three unchanged EKGs, and then consider deescalating monitoring to every 3 days.

Additional reading

Beach SR et al. QT Prolongation, torsades de pointes, and psychotropic medications: A 5-year update. Psychosomatics. 2018;59(2):105-22. doi: 10.1016/j.psym.2017.10.009.

Drew BJ et al. Prevention of torsades de pointes in hospital settings: A scientific statement from the American Heart Association and the American College of Cardiology Foundation. Circulation. 2010;121(8):1047-60. doi: 10.1161/CIRCULATIONAHA.109.192704.

Zolezzi M, Cheung L. A literature-based algorithm for the assessment, management, and monitoring of drug-induced QTc prolongation in the psychiatric population. Neuropsychiatr Dis Treat. 2019;15:105-14. doi: 10.2147/NDT.S186474.

Quiz

A 70-year-old male inpatient on furosemide with last known potassium level of 3.3 is going to be started on olanzapine. His baseline EKG has a QTc of 470 ms.

How often should he receive EKG monitoring?

A. Daily

B. Every 3 days

C. Weekly

D. Monthly

Answer (C): He is a low risk patient (6 points: over 70 yrs, loop diuretic, K+< 3.5, QTc > 450 ms), so he should receive weekly EKG monitoring.