Chloroquine-induced QTc prolongation in COVID-19 patients

Background In the battle against the SARS-CoV-2 pandemic, chloroquine has emerged as a new potential therapeutic option for the treatment of infected patients. A safety consideration for the application of chloroquine is its QTc-prolonging potential. Thus far, no data are available on the QTc-prolonging potential of chloroquine in COVID-19 patients. Objective To assess the degree of chloroquine-induced QTc prolongation in hospitalised COVID-19 patients. Methods A baseline electrocardiogram (ECG) and ECGs recorded during chloroquine treatment were retrospectively collected in patients suspected of having COVID-19. The QTc interval was calculated by computerised and manual interpretation. Baseline and follow-up QTc intervals were compared using the paired samples t-test. Results A total of 95 patients had a baseline ECG recording and at least one ECG recording during chloroquine therapy. Chloroquine treatment resulted in a mean QTc prolongation of 35 & x202f;ms (95% CI 28-43 & x202f;ms) using computerised interpretation and 34 & x202f;ms (95% CI 25-43 & x202f;ms) using manual interpretation. No torsade de pointes was observed during chloroquine treatment. After manual review, 22 patients (23%) had a QTc interval exceeding 500 & x202f;ms during chloroquine treatment. None of these patients had a prolonged QTc interval prior to the initiation of chloroquine treatment. Conclusions Chloroquine significantly prolongs the QTc interval in a clinically relevant matter. This highlights the need for ECG monitoring when prescribing chloroquine to COVID-19 patients.