Management of DR-TB ADR: QT Prolongation

QT prolongation is a condition in which repolarization of the heart after a heartbeat is affected. 

It results in an increased risk of an irregular heartbeat which can result in shortness of breath or chest pain, fainting, seizures or cardiac arrest. 

If patients experience such signs or symptoms, health workers need to refer such patients to the nearest health facility where Electrocardiogram (ECG) can be done and further management initiated.

Suspected agent(s): Bedaquiline (Bdq), Fluoroquinolone (FQ), Clofazimine (Cfz)

Suggested Management Strategies

• Values above Corrected QT Interval by Fridericia (QTcF) 450 ms in males and 470 ms in females are referred to as prolonged. Patients with prolonged QTcF are at a risk for developing cardiac arrhythmias like Torsades de Pointes, which can be life-threatening.
• Fluoroquinolone (FQ) may cause prolongation of the QTcF; Moxifloxacin (Mfx) and Gatifloxacin (Gfx) cause the greatest QTcF prolongation, while Levofloxacin (Lfx) and Ofloxacin (Ofx) have a lower risk.
• Currently, ECG monitoring prior to initiation and during Drug-resistant TB (DR-TB) treatment is only required with the use of Bdq or when two drugs known to prolong QTcF (e.g., Mfx, Cfz) are combined in the same regimen.
• Low serum levels of potassium, calcium and magnesium are associated with QTc prolongation. Electrolyte levels should be maintained in the normal range in any patient with an elevated QT interval.
• Avoid other drugs that increase the QT interval.
• QT prolongation can result in ventricular arrhythmias (Torsades de Pointes) and sudden death. It is therefore imperative that ECGs be used to monitor the QT interval regularly during the use of the suspected drugs.
• QTcF value between 450-480 ms: Rule out other causes of prolonged QTc, before deciding to withhold the suspected agents.
• Management of increased QTcF entails looking at the algorithm for the reintroduction of anti-TB drugs (Bdq/ Delamanid (Dlm)/ FQ/ Cfz) once prolonged QTc has normalised.

Resources

• Guidelines for Programmatic Management of Drug-resistant Tuberculosis in India, March 2021.
• WHO Consolidated Guidelines on Tuberculosis: Module 4 – Treatment: Drug-resistant TB Treatment, 2020.
• Technical and Operational Guidelines for TB in India, 2016.

​ Kindly provide your valuable feedback on the page to the link provided HERE