Now as US FDA has issued an emergency use authorization to allow hydroxychloroquine and chloroquine used for certain hospitalized patients with COVID-19, it is useful to know some risk predictors in those using drug in view of its much debated pro-arrhythmic potential.
American college of cardiology has recently published an article regarding same.
Following are some precautionary measures and we should evaluate Risk Vs Benefit in each case
- Baseline Evaluation
- Avoid all other non-critical QT prolonging agents.
- Assess a baseline ECG, renal function, hepatic function, serum potassium and serum magnesium.
- When possible, have an experienced cardiologist measure QTc.
- Baseline QT prolongation is a contraindication
- History of sudden cardiac death in family -rule out arrhythmic cause
- Calculate risk assessment (see below) in each case with risk benefit ratio.
- Ongoing monitoring, dose adjustment and drug discontinuation
- Place on telemetry prior to start of therapy.
- Monitor and optimize serum potassium daily.
- Acquire an ECG 2-3 hours after the second dose of hydroxychloroquine, and daily thereafter.
- If QTc increases by >60 msec or absolute QTc >500msec (or >530-550 msec if QRS >120 msec), discontinue azithromycin (if used) and/or reduce dose of hydroxychloroquine and repeat ECG daily.
- If QTc remains increased >60 msec and/or absolute QTc >500 msec (or >530-550 msec if QRS >120 msec), reevaluate the risk/benefit of ongoing therapy, consider consultation with an cardiologist and consider discontinuation of hydroxychloroquine.
Table 1. Tisdale Risk Score For Drug-Associated QTc Prolongation
|Age ≥68 y||1|
|Serum K+ ≤3.5 mEq/L||2|
|Admission QTc ≥450 ms||2|
|≥2 QTc-prolonging drugs||3|
|One QTc-prolonging drug||3|
|Maximum Risk Score||21|
|K+ indicates potassium; and MI, myocardial infarction.|
Table 2. Risk Levels For Drug-Associated QT Prolongation
|Low risk = ≤6 points|
|Moderate risk = 7-10 points|
|High-risk = ≥11 points|
Hope it helps some one
Good day !
Timothy F. Simpson, MD, PharmD; Richard J. Kovacs, MD, FACC; and Eric C. Stecker, MD, MPH, FACC.Ventricular Arrhythmia Risk Due to Hydroxychloroquine-Azithromycin Treatment For COVID-19 Acc Cardiology magazine Mar 29 2020
Tisdale JE, Jayes HA, Kingery JR, et al. Development and validation of a risk score to predict QT interval prolongation in hospitalized patients. Circ Cardiovasc Qual Outcomes. 2013;6:479-487.