What is a key cardiac safety concern with bedaquiline and delamanid?

• A. Nephrotoxicity.
• B. Ototoxicity.
• C. Hepatotoxicity.
• D. QT interval prolongation; monitor with ECG.

Answer: (D)

Prolongation of the QT interval on the ECG is the primary cardiac safety concern with these drugs. Bedaquiline and delamanid can lengthen the time it takes for the heart’s ventricles to repolarize, often by affecting cardiac ion channels such as the hERG potassium channel. This lengthening raises the risk of dangerous rhythms like torsades de pointes, especially if there are electrolyte disturbances (low potassium or magnesium) or if other QT-prolonging medications are also used.

Because of this risk, the safety approach focuses on ECG monitoring and electrolyte management. Before starting therapy, obtain a baseline ECG; then repeat ECGs after initiation and after any dose changes, with periodic checks during treatment. Correct electrolytes as needed and avoid or limit other drugs that further prolong the QT interval. If the QTc becomes very long (for example, exceeding about 500 ms, or increasing substantially from baseline), clinicians may need to adjust or discontinue therapy.

Other toxicities can occur with TB drugs, but the specific cardiac safety concern here is QT interval prolongation and the need for ECG monitoring.