In a child receiving pediatric multidrug‑resistant tuberculosis treatment with bedaquiline and delamanid, how can QT‑interval risk be monitored when an ECG is unavailable?

Monitoring QT-Interval Risk Without ECG Access

When ECG monitoring is unavailable in children receiving bedaquiline and/or delamanid for MDR-TB, less frequent ECG monitoring can be considered after 8 weeks if baseline and early follow-up QTc intervals are normal, though this represents a compromise rather than ideal practice 1.

Practical Monitoring Strategy When ECG Access is Limited

Initial Assessment (Critical - Cannot Be Skipped)

• Baseline ECG is mandatory before starting bedaquiline or delamanid 1
• Contraindications that preclude treatment without ECG:
  • Delamanid: Baseline QTc >500 ms that doesn't correct with medical management 1
  • Bedaquiline: Baseline QTc >450 ms that doesn't correct, patient/family history of cardiac arrhythmias, or severe cardiac disease 1

Modified Monitoring Schedule for Resource-Limited Settings

Standard recommendation: Monthly ECG monitoring throughout treatment 1

Acceptable compromise when ECG access is challenging 1:

• Baseline ECG (mandatory)
• Week 2 ECG
• Week 4 ECG
• Week 8 ECG
• If all early ECGs show normal QTc intervals: Consider reducing frequency after week 8
• Resume more frequent monitoring if any clinical concerns arise

Clinical Surveillance Without ECG

When ECG is temporarily unavailable, monitor for:

• Cardiac symptoms: Palpitations, syncope, dizziness, chest pain
• Electrolyte disturbances: Ensure adequate potassium and magnesium levels (hypokalemia and hypomagnesemia increase QT prolongation risk) 1
• Drug interactions: Avoid adding other QT-prolonging medications
• Albumin levels: Check monthly with delamanid 1

Risk Mitigation Strategies

Drug selection considerations:

• Prefer delamanid over bedaquiline in children when ECG monitoring is limited, as delamanid has more pediatric safety data 1
• Substitute levofloxacin for moxifloxacin when possible, as levofloxacin has less QTc effect 1
• Avoid combining multiple QT-prolonging agents when monitoring is limited (e.g., clofazimine + moxifloxacin showed 13 ms greater QTc increase) 2

Important Caveats

This is not ideal practice: The guideline-recommended monthly ECG monitoring exists because QTc prolongation can occur at any point during treatment 1. Recent data shows:

• Peak QTc prolongation typically occurs at weeks 10-14 3
• 2.1% of children on clofazimine-containing regimens may develop QTc >500 ms 2
• Most significant prolongation occurs within first 12 weeks 4

When ECG is completely unavailable: Consider whether the benefits of these novel agents outweigh risks. The guidelines state that "if adverse events cannot be monitored, linezolid is best used in patients with additional resistance or intolerance to other second-line medications" 1, suggesting similar caution applies to bedaquiline and delamanid.

Absolute requirement: You cannot start bedaquiline or delamanid without at least a baseline ECG to rule out contraindications 1. If no ECG access exists at all, these drugs should not be initiated.