ABC | Volume 114, Nº6, June 2020

Viewpoint Wu et al. Preventing Torsades de Pointes during Hydroxychloroquine/Azithromycin Treatment Arq Bras Cardiol. 2020; 114(6):1061-1066 the method (ECG, telemetry, or devices) be determined according to patients’ risks, based on an initial QTc (upon admission to the hospital). Figure 4 outlines the proposed control model. Initial risk assessment for treatment according to baseline QT measurement on 12-lead ECG: QTc ≤ 450 ms Approved for use 450ms < QTc ≤ 470 ms Use with caution or only in the hospital 470ms < QTc < 500 ms Avoid or only use in the hospital with telemetry QTc ≥ 500 ms Avoid, considering risk/benefit In cases where doubts exist or in borderline measurements regarding greater risk throughout the treatment, it is possible to opt for isolated use of HCQ or AZ, or also for staggered use of HCQ, followed by AZ, under monitoring. It is recommended that a shared decision be reached with the hospital’s cardiology or arrhythmia team. When to repeat ECG during treatment in the hospital, according to previous QTc QTc ≤ 450 ms On day 2 450 ms < QTc ≤ 470 ms On day 2 470 ms < QTc < 500 ms On days 2 and 4 QTc ≥ 500 ms 4 to 8 hours after the first dose, then daily Control should be intensified in the following conditions: - If there are associated risk factors (Table 1). - In the presence of cardiovascular complications, such as myocarditis and myocardial ischemia. N.B.: Figures 5 and 6 show suggested models for pre- treatment and control checklists. Warning signs - Increase in QTc by > 60 ms and/or by more than 10% with respect to baseline ECG. - QTc above 520 ms: evaluate suspending treatment after other drugs (those that are dispensable and that have a synergistic effect on QTc) have been suspended, or electrolyte disturbance. - Need to add medications that prolong the QT interval, according to the patient’s clinical evolution. - Presence of ventricular arrhythmias and/or associated bradycardia -> Choose the drugs that can be suspended according to the risk-benefit ratio. In these situations, it is necessary to keep the patient on continuous telemetry. Additional care measures for preventing TdP Regarding electrolyte control upon hospital admission: Measurements of calcium, potassium, and magnesium, which are essential for the stability of ventricular repolarization, should be carried out for all patients eligible for treatment with HCQ/AZ. Figure 4 – Suggested HCQ and / or AZ treatment control scheme. 1063