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Flecainide toxicity: ECG changes associated with supratherapeutic levels in milk-fed infants
  1. Hitarth Bhatt,
  2. Will Regan,
  3. Eric Rosenthal and
  4. Hannah Bellsham-Revell
  1. Paediatric Cardiology, Evelina London Children's Hospital, London, UK
  1. Correspondence to Dr Hitarth Bhatt; hitarth.bhatt{at}


Flecainide is a class 1C antiarrhythmic and is highly effective for treating a wide range of arrhythmias. It is not licensed for children under the age of 12 years, but has been used safely for years in young children, particularly when first-line agents are not effective. Although toxicity does occur in both adult and paediatric populations, there have been very few reported instances of flecainide toxicity in neonates and children. Supratherapeutic levels of flecainide manifests on ECG with prolongation of the PR interval, QRS duration and QT, and can lead to life-threatening arrhythmias. In milk-fed infants receiving flecainide, regular feeding patterns are paramount to achieve a steady therapeutic state, as milk and dairy products are known to reduce the absorption of flecainide. This case series details four milk-fed infants admitted with ECG changes secondary to flecainide toxicity.

  • Cardiovascular system
  • Paediatrics (drugs and medicines)
  • Arrhythmias
  • Neonatal and paediatric intensive care
  • Unwanted effects / adverse reactions

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  • Contributors Patients were under the care of WR and ER and they identified the need for a case series. The report was designed and written by HB. WR obtained parental consent and reviewed all the drafts. ER and HB-R reviewed the final draft and provided cardiology and electrophysiology expertise. All authors contributed to the editing of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

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