Summary

The authors describe a 28-year-old woman with newly diagnosed acute promyelocytic leukaemia (APL), who developed junctional bradycardia after receiving the molecular-targeted therapy all-trans retinoic acid (ATRA) and the anthracycline-based chemotherapeutic agent idarubicin following sepsis and the APL differentiation syndrome. The patient was asymptomatic of the bradycardia. Electrolytes and cardiac imaging were unremarkable. No other cases have been reported in this context and the mechanisms of the sinus node dysfunction are unclear. The patient achieved normal sinus rhythm after ATRA was withheld. The patient recovered and went on to achieve complete remission after re-starting ATRA and idarubicin.