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Progressive Conduction System Disease in Hydroxychloroquine Cardiotoxicity: A Call for Early Vigilance

Milica Vukićević1, Mandeep R Mehra2, Robert F Padera3

  • 1Center for Advanced Heart Disease, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Cardiac Surgery Clinic, University Clinical Center of Serbia, Belgrade, Serbia.

The American Journal of Cardiology
|November 23, 2025
PubMed

Insights

Hydroxychloroquine (HCQ) can cause deadly heart conduction problems. This case shows HCQ toxicity damages heart nodes, leading to irreversible injury and sudden death, even with pacing.

Area of Science:

  • Cardiology
  • Toxicology
  • Pathology

Background:

  • Hydroxychloroquine (HCQ) cardiotoxicity is a growing concern.
  • Progressive conduction system disease is an underrecognized, potentially lethal HCQ side effect.

Purpose of the Study:

  • To report a case of fatal HCQ-induced cardiotoxicity.
  • To highlight the lysosomal mechanism of HCQ toxicity in cardiac conduction.

Main Methods:

  • Case report of a 67-year-old female on chronic HCQ.
  • Clinical presentation, management with atrial pacing, and autopsy findings.

Main Results:

  • Patient developed progressive conduction abnormalities, cardiogenic shock, and sudden death.
  • Autopsy revealed sinoatrial and atrioventricular nodal lysosomal toxicity and fibrosis.

Conclusions:

  • HCQ cardiotoxicity can manifest as primary, irreversible conduction system disease.
  • Lysosomal damage underlies HCQ's lethal cardiac effects.
  • ECG monitoring and early dual-chamber pacing may prevent adverse outcomes.

Keywords:
cardio-toxicityconduction system diseasehydroxychloroquinelysosomal destruction

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