The Electrocardiograms (ECG) and Monitoring
The ECGs on admission were evaluated among the patients who received HCQ. Lead II was utilized for the measurement of the QTc interval on ECG or on telemetry. The end of the T-wave was defined as the tangent drawn from the steepest last limb of the T-wave to its intersection with the baseline. Bazett’s formula was used to calculate the corrected QT (QTc) interval. If the baseline QTc level is below 450 ms, ECG re-evaluated on the third to fifth day of HCQ treatment; if the QTc levels are between 450-499 ms ECG evaluated daily. Critical QTc prolongation was defined as prolongation of QTc or ∆QTc levels (>500 msn, >60 msn; respectively). If a baseline bundle branch block (QRS >120 ms) was present, critical prolongation of QTc interval was accepted as 550 ms(Helfenbein et al., 2006).