Revisiting QT prolongation in acute rheumatic fever - Relevance for hydroxychloroquine treatment

In-vitro evidence suggests hydroxychloroquine could be a potential immunomodulator for the inflammatory carditis of acute rheumatic fever (ARF). Hydroxychloroquine used as an anti-inflammatory agent has a low side effect profile but its use in the Covid-19 pandemic raised concerns about QTc interval prolongation and cardiac arrhythmias. The prolongation of QTc in ARF appears benign but has not been widely studied. We aim to report QTc intervals in a contemporary ARF population and consider implications for hydroxychloroquine use in ARF. The study cohort was 197 children <15 years of age with a clinical diagnosis of ARF. The QTc mean (SD) was 445 msec (28), range 370-545 msec. Eighteen percent of the cohort had a QTc > 99th percentile for normal by age and 8 patients (4%) had a QTc over 500 msec. There was no difference of QTc by age or gender. Inter-observer repeatability for QTc (n = 33) was 35 msec. The QTc is often prolonged in the early phase of ARF, meaning that QT prolonging medications should be used with caution in this setting. Serial ECG monitoring of the QT interval is recommended if hydroxycholoroquine is used in ARF.