QT Prolongation: Risk Factors and Considerations - #100Take Quiz
Review medical conditions and medications that can prolong QT
When treating older adults, it is important to remember that the QT interval is prolonged when it is over 450 ms in men and over 470 ms in women. QT prolongation may progress to torsades des pointes, which can then develop into potentially fatal cardiac arrhythmias. Obtaining EKGs to monitor the QT along with awareness of risk factors for prolongation can help decrease this risk and inform safe medication choices.
Antipsychotic medications are associated with increased risk of ventricular arrhythmias and sudden cardiac death. The risk is noted to be higher in short-term use of antipsychotic medications as opposed to long-term use. Additionally, some studies have noted higher risk in typical antipsychotics, especially in older individuals with pre-existing cardiac conditions. Other psychotropic medications with higher potential to prolong the QT are lithium and the tricyclic antidepressants.
The below chart outlines known risk factors for QT prolongation. While some risks factors are static, many risk factors can be mitigated. Numerous classes of medications are known to lead to QT prolongation. Safer alternatives for psychotropic medications are provided. It is important to recognize that information on QT prolonging medications is constantly evolving; reviewing medications and checking the literature for updates is beneficial. Also note that medications and supplements can interfere with the metabolism of QT prolonging medications.
Age (over 65)
Structural heart disease
Multiple QT prolonging meds
Increased dose of prolonging agents
Hypokalemia (under 3.5)
Higher Risk Offenders
Class IA agents(quinidine)
Class III agents (amiodarone, sotalol, ibutilide, dofetilide)
Diuretics (thiazides, furosemide)
Antipsychotics (ziprasidone, haloperidol, chlorpromazine)
Extracts that inhibit CYP3A4, or have diuretic properties
-**less data on newer agents
- Obtain a baseline EKG. A baseline EKG is important to obtain prior to starting a medication that has the potential to prolong the QT. This will inform medication options.
- Prolonged QTc? Check for tachycardia and consider utilizing the Fridericia or Framingham calculation of QTc. If the QTc is prolonged, look at the rate listed on the EKG; EKGs utilize Bazett for their calculation of QTc. If the individual is tachycardic, the QTc will be over-estimated; consideration for the Fridericia or Framingham should be given.
- Make sure K > 4.0 mmol/l, Mag > 2.0 mmol/l. Making sure electrolytes are repleted is important as low electrolytes are risk factors for QT prolongation.
- Repeat EKG. After starting a medication that can prolong the QT, repeat an EKG within a few days to monitor for changes. If the dose of a medication that prolongs QT is adjusted, also repeat an EKG.
- Pt has prolonged QT but requires medications that can further prolong the QT. If medications are required that impact the QT in an individual with a prolonged QT (especially if that QTc is >500), involvement of cardiology is highly encouraged.
This GFF reviews individual risk factors for prolonged QT and common medications that can prolong the QT.
Decide the safest pharmacologic options in relation to the risk of QT prolongation. For individuals with a prolonged QT, consider lower risk treatment options when possible. Better recognize medications that pose a higher risk.
Recognize and mitigate risk factors for QT prolongation
Review of Systems (ROS)
Beach, S. R., Celano, C. M., Sugrue, A. M., Adams, C., Ackerman, M. J., Noseworthy, P. A., & Huffman, J. C. (2018). QT prolongation, torsades de pointes, and psychotropic medications: a 5-year update. Psychosomatics, 59(2), 105-122.
Desai, N., Venkatesh, C. R., & Kumar, S. S. (2015). QT prolongation and torsades de pointes with psychotropic agents. Indian journal of psychiatry, 57(3), 305–308. https://doi.org/10.4103/0019-5545.166619
Funk, K. A., & Bostwick, J. R. (2013). A comparison of the risk of QT prolongation among SSRIs. Annals of Pharmacotherapy, 47(10), 1330-1341.
Gupta, A., Lawrence, A. T., Krishnan, K., Kavinsky, C. J., & Trohman, R. G. (2007). Current concepts in the mechanisms and management of drug-induced QT prolongation and torsade de pointes. American heart journal, 153(6), 891-899.
Isbister, G. K., & Page, C. B. (2013). Drug induced QT prolongation: the measurement and assessment of the QT interval in clinical practice. British journal of clinical pharmacology, 76(1), 48-57.
Jankelson, L., Karam, G., Becker, M. L., Chinitz, L. A., & Tsai, M. C. (2020). QT prolongation, torsades de pointes, and sudden death with short courses of chloroquine or hydroxychloroquine as used in COVID-19: A systematic review. Heart rhythm, 17(9), 1472-1479.
Li, M., & Ramos, L. G. (2017). Drug-induced QT prolongation and torsades de pointes. Pharmacy and Therapeutics, 42(7), 473.
Liperoti, R., Gambassi, G., Lapane, K. L., Chiang, C., Pedone, C., Mor, V., & Bernabei, R. (2005). Conventional and atypical antipsychotics and the risk of hospitalization for ventricular arrhythmias or cardiac arrest. Archives of Internal Medicine, 165(6), 696-701.
Owens, R. C. (2004). QT prolongation with antimicrobial agents. Drugs, 64(10), 1091-1124.
Stöllberger, C., Huber, J. O., & Finsterer, J. (2005). Antipsychotic drugs and QT prolongation. International clinical psychopharmacology, 20(5), 243-251.
Swenson, R. S., & Murphy-Ende, K. (2020). Prolonged QT interval in patients receiving psychotropic medications. Journal of the American Psychiatric Nurses Association, 26(4), 344-353.
Vandenberk, B., Vandael, E., Robyns, T., Vandenberghe, J., Garweg, C., Foulon, V., ... & Willems, R. (2016). Which QT correction formulae to use for QT monitoring?. Journal of the American Heart Association, 5(6), e003264.
Wu, C. S., Tsai, Y. T., & Tsai, H. J. (2015). Antipsychotic drugs and the risk of ventricular arrhythmia and/or sudden cardiac death: a nation‐wide case‐crossover study. Journal of the American Heart Association, 4(2), e001568.
Yap, Y. G., & Camm, A. J. (2003). Drug induced QT prolongation and torsades de pointes. Heart, 89(11), 1363-1372.
Examples of lists online of QT Prolonging Medications: