Chloroquine and arrhythmia

Dear friends,

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

  1. Baseline Evaluation
    1. Avoid all other non-critical QT prolonging agents.
    2. Assess a baseline ECG, renal function, hepatic function, serum potassium and serum magnesium.
    3. When possible, have an experienced cardiologist measure QTc.
    4. Baseline QT prolongation is a contraindication
    5. History of sudden cardiac death in family -rule out arrhythmic cause
    6. Calculate risk assessment (see below) in each case with risk benefit ratio.
  2. Ongoing monitoring, dose adjustment and drug discontinuation
    1. Place on telemetry prior to start of therapy.
    2. Monitor and optimize serum potassium daily.
    3. Acquire an ECG 2-3 hours after the second dose of hydroxychloroquine, and daily thereafter.
    4. 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.
    5. 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

Risk FactorsPoints
Age ≥68 y1
Female sex1
Loop diuretic1
Serum K+ ≤3.5 mEq/L2
Admission QTc ≥450 ms2
Acute MI2
≥2 QTc-prolonging drugs3
Heart failure3
One QTc-prolonging drug3
Maximum Risk Score21
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

For further reading log on to

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.

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