Is azithromycin (azithromycin) safe for a patient with a prolonged QTc interval to treat typhoid fever?

Azithromycin Use in a Patient with Left Axis Deviation and Inverted T Waves

Azithromycin can be safely used for typhoid fever in this patient with a QTc of 388 ms, as this value is within normal range, but ECG monitoring is recommended after starting treatment.

Assessment of Current Cardiac Status

The patient's current ECG findings include:

• Left axis deviation
• Inverted T waves in lead V1
• QTc interval of 388 ms

This QTc value is within normal limits (normal is <450 ms for men and <470 ms for women) 1, making the patient a suitable candidate for azithromycin therapy. The inverted T waves in V1 may be a normal variant, particularly if the patient has no cardiac symptoms.

Safety of Azithromycin in This Context

Azithromycin has several advantages for treating typhoid fever:

• It has demonstrated excellent efficacy against Salmonella typhi 2, 3, 4, 5
• It has a "very low risk of TdP" (Torsades de Pointes) compared to other macrolides 1
• It can be used in areas with high rates of multidrug resistance 2

Recommended Treatment Approach

1. Confirm baseline cardiac safety:

   • The current QTc of 388 ms is well below the threshold of concern (450 ms for men, 470 ms for women)
   • This makes azithromycin a suitable option for this patient 1

2. Recommended dosing for typhoid fever:

   • Azithromycin 500 mg twice daily on day 1, followed by
   • Azithromycin 500 mg once daily for 6 days 3, 4
   • This regimen has shown excellent efficacy in clinical trials for typhoid fever

3. Monitoring recommendations:

   • Obtain a follow-up ECG after 2-3 doses to check for QTc prolongation 1
   • If QTc increases to >450 ms (men) or >470 ms (women), consider discontinuation 1

Important Precautions

While azithromycin is likely safe in this patient, be aware of:

• Drug interactions: Avoid co-administration with other QT-prolonging medications 1, 6
• Electrolyte monitoring: Ensure potassium and magnesium levels are normal, as electrolyte abnormalities can increase arrhythmia risk 1
• Patient education: Instruct the patient to report any palpitations, dizziness, or syncope immediately 1

Alternative Options

If concerns about cardiac effects arise during treatment:

• Ceftriaxone is an effective alternative for typhoid fever without QT-prolonging effects
• Trimethoprim-sulfamethoxazole may be considered if susceptibility is confirmed

Conclusion

Based on the current ECG findings with a normal QTc interval of 388 ms, azithromycin is a safe and effective choice for treating this patient's typhoid fever. The British Thoracic Society guidelines specifically note that macrolides should be avoided only in patients with a prolonged QTc interval (>450 ms for men and >470 ms for women) 1, which does not apply to this patient.

A recent study in ICU patients showed no significant QTc prolongation with azithromycin use 7, further supporting its cardiac safety in patients with normal baseline QTc intervals.