QT Interval Prolongation in Patients Treated for COVID-19

Background Many of the drugs commonly used for the treatment of COVID-19 cause QT interval prolongation and increase the risk of life-threatening cardiac arrhythmias. It has been shown that maintaining serum potassium and magnesium levels above 4 and 3 mg/dL, respectively, would prevent the QTc prolongation. Objective To determine if keeping only the serum magnesium level above 3 mg/dL could be considered an effective measure to prevent QTc prolongation in patients with COVID-19 receiving these drugs. Methods In a retrograde observational study, QTc interval was measured in 14 patients diagnosed with COVID-19 before and 3 days after initiation of treatment with either hydroxychloroquine or lopinavir-ritonavir, while their serum magnesium levels were kept ≥3 mg/dL. Results The baseline QTc interval of 412 (SD 36) ms significantly increased by an average of 34 (95% CI 13 to 55) ms after 3 days of treatment. 5 patients, mostly those with lower serum potassium levels, had QTc prolongation ≥60 ms. Conclusion Although it seems that the risk of fatal cardiac arrhythmias in this setting is not high, it is prudent to monitor the serum electrolytes, particularly potassium, in patients with COVID-19 who are treated with either hydroxychloroquine or lopinavir-ritonavir.