Hydroxychloroquine- and Azithromycin-Induced Transient Left-Bundle Branch Block in a Patient with COVID-19

Abstract

Background: COVID-19 has emerged and rapidly spread worldwide due to the high infectivity of the novel coronavirus. A new regimen consisting of a combination of hydroxychloroquine and azithromycin has been under evaluation for efficacy and side effects, especially cardiotoxicity. Case summary: A 58-year-old man was admitted to the hospital for COVID-19 pneumonia. His initial ECG showed sinus tachycardia. He was started on combination therapy of azithromycin and hydroxychloroquine. After the second dose of hydroxychloroquine and initial dose of azithromycin, his ECG showed complete left-bundle branch block (LBBB). The treatment was stopped, and the patient had no cardiac symptoms. On Day 8 of admission, his repeat ECG showed an absence of LBBB. Discussion: The cumulative dose of hydroxychloroquine observed in patients treated for malaria or systemic diseases is cardiotoxic, and few cases of LBBB, have been reported. It is, however, not known whether the use of azithromycin in association with a small dose of hydroxychloroquine induces transient LBBB.