Abstract 15320: The Effects of Hydroxychloroquine on Electrocardiogram Intervals

Abstract

Background: Hydroxychloroquine (HCQ) was widely used as a potential therapy for COVID-19 infection. We studied the effects of HCQ on electrocardiogram (ECG) intervals. Methods: We conducted a large-scale retrospective study of COVID-19 patients treated with HCQ admitted between March 1, 2020 and June 1, 2020. Extensive medical chart review was performed. Baseline and on treatment ECG intervals were manually measured by 3 electrophysiologists. The QT interval was corrected using Bazett formula (QTc). The paired t-test was used for the main analysis. Results: Paired ECG data from 1890 patients were analyzed. The mean age was 47.0 (±12.6) years with a strong male prevalence (85.6%). The commonest comorbidities were hypertension (39.6%) and diabetes mellitus (36.8%). The average duration of HCQ therapy was 6.3 (±2.3) days. 404 patients (21.4%) had severe COVID-19 infection and the mortality rate was 3.86%. Intensive care admission and mechanical ventilation was required in 209 (11.1%) and 166 (8.8%) patients, respectively. During therapy, heart rate (HR) decreased from 87.2 ± 16.8 bpm to 80.6 ± 14.7 bpm ( P <0.001). The mean PR interval increased from 153.2 ± 21.9 ms to 162.9 ± 22.8 ms ( P <0.001). The mean QRS duration increased from 92.8 ± 12.6 ms to 97.4 ± 13 ms ( P <0.001). The average QTc increased from 427.4 ± 25.4 ms to 438.4 ± 29.9 ms ( P <0.001). Conclusions: HCQ caused a modest but statistically significant prolongation in PR, QRS and QTc intervals. A reduction in HR was also noted mainly due to clinical improvement.