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Lack of effect of azithromycin on QT interval in children: a cohort study
  1. David Espadas,
  2. Silvia Castillo,
  3. Marcela Moreno,
  4. Amparo Escribano
  1. Pediatric Pulmonology Unit, University Clinical Hospital of Valencia, University of Valencia, Valencia, Spain
  1. Correspondence to Professor Amparo Escribano, Unidad de Neumología Infantil, Hospital Clínico Universitario de Valencia. Av. Blasco Ibáñez, 17., Valencia 46010, España; aescribano{at}

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Macrolides are a group of antimicrobial drugs used widely, being well known for their adverse cardiac effects. Erythromycin and clarithromycin are most commonly associated with these conditions. In recent years, azithromycin (AZM) has been assessed because of its possible relation to arrhythmias (mainly QT interval prolongation) and risk of cardiovascular death.1 The pharmacodynamics of these effects is complex and the occurrence of cardiovascular death is unpredictable.2 However, all published manuscripts on the cardiac effects of AZM to date are cases in adults or elderly patients with heart disease or other comorbidities, without any information about the paediatric population. AZM is the most used macrolide in children with chronic respiratory disease because of its immunomodulatory and anti-inflammatory effects.3 ,4 For this reason, we proposed to study the possible negative effects of AZM on myocardial repolarisation in children with a variety of chronic pulmonary diseases that require long-term AZM treatment.

For 33 months, we studied a cohort of 86 paediatric patients in the paediatric respiratory unit in a university tertiary hospital. All of them were receiving treatment with AZM for a minimum period of 3 months, on a single daily dose of 10 mg/kg, 3 days a week.

All children underwent an ECG in which a paediatrician and a paediatric cardiologist measured the corrected QT (QTc), (mean 12 leads), and assessed the presence of any other heart arrhythmias. Any time longer than 440 ms was considered prolonged QTc.

The children studied had a mean age of 6.6 years. There were no differences in sex (47 female (55%). Fourteen patients had a history of prematurity. At the time of inclusion in the study, 77 (89.5%) were receiving treatment for underlying lung disease, and 13 (15%) used other drugs with effects on QTc, such as ciprofloxacin, domperidone or sulfamethoxazole/trimethoprim.

All the children had some recurrent or chronic lung disease (figure 1) and were being treated with AZM because of its anti-inflammatory/immunomodulatory effects. The mean duration of this treatment was 5 months (3–72 months). The mean QTc was 381.5 ms and the values ranged from 326 to 430 ms. In all cases, QTc measurement was <440 ms (figure 2). There were no cases of other arrhythmias and no deaths.

Figure 1

Distribution of respiratory diseases.

Figure 2

Representation QTc values.

In conclusion, long-term treatment with AZM does not seem to cause heart rhythm disorders or QTc prolongation in children with chronic respiratory disease. Despite our findings, we think it is important that all children undergo cardiac evaluation before starting treatment with AZM.


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  • Competing interests None declared.

  • Patient consent Parental/guardian consent obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.