QT Interval of patients with SARS-CoV-2 Infection treated with Hydroxychloroquine/Azithromycin

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Salient Points

This article focuses on the change in the QT interval in a study conducted on 84 adult patients with SARS-CoV-2 infection who were being treated with Hydroxychloroquine/ Azithromycin combination.

QTc was prolonged between day 3 and 4 in 30% of patients with increased QTc by greater than 40ms. In 11% of patients QTc was increased > 500 ms.

This represented a high risk group for irregular rhythm.

Detailed Summary

Results of study

  • The average time of ECG follow up post HCQ/AZ exposure was 4.3+/- 1.7 days.
  • The OTc interval prolonged from a baseline of 435+/- 24 ms to a maximum value of 463 +/- 32 ms
  • The maximum value occurred on day 3.6+/- 1.6 of therapy
  • 11% of patients developed severe QTc prolongation of > 500ms. This increases risk of malignant arrhythmia and Sudden Cardiac Death.
  • Development of ARF was a significant predictor of severe QTc prolongation.
  • Patients treated with HCQ/AZ, QTc were prolonged significantly.


Patients treated with Hydroxychloroquine/ Azithromycin were observed to have an increase in QT interval on ECG. Patients on HCQ/ AZ combination should have regular ECG and QTc monitoring.

Reference Link : https://www.medrxiv.org/content/10.1101/2020.04.02.20047050v1

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