Table 6.

Step-wise actions to be followed for starting patients on chloroquine or hydroxychloroquine.

Purpose: To prevent long QTc interval, Torsade de Pointes causing polymorphic ventricular tachycardia and sudden cardiac deaths.
Step	Particulars	Action
1	Check: known drug allergy congenital long QT syndrome (occurs in 1:7000)	Drug contraindicated
2	Check: drug interaction refer to Table 4, Table 5 for a list of drugs that have a drug interaction with CQ or HCQ	Stop non-essential drugs that have a drug interaction
3	Check: the risk score for QTc prolongation total score: 21. Score ≤ 6 (risk low, chance 15%); 7–10 (risk moderate, chance 37%); ≥ 11 (risk high, chance 73%) Risks include: age ≥ 68 years - 1, female gender - 1, concomitant loop diuretic - 1, serum K+ ≤ 3.5 mEq/L - 2, admission QTc ≥ 450 ms - 2, acute MI - 2, sepsis - 3, heart failure - 3, one QTc-prolonging drug - 3, ≥ 2 QTc-prolonging drugs – 3, additional points i.e. 6	Drug contraindicated when risk is high (score ≥ 11)
4	Calculate baseline QTc: {QT interval - start of the Q wave to the end of the T wave; QTc = QT / √ RR, use an app to calculate QTc. Normal ≤ 430 ms (male)/≤ 450 ms (female)}(75)	Drug contraindicated if baseline QTc ≥ 500 ms
5	Monitor: serum K+ and Mg+ use of loop diuretics	Correct electrolyte imbalance
6	Plan: interval ECG (12 hourly) or cardiac telemetry in sick patients interval ECG in ambulatory subjects	Reduce dose if QTc prolongs, stop the drug if QTc ≥ 500 ms
	In case of Torsade de Pointes: stable tachycardia - give magnesium sulfate 1–2 g IV x 15 min not responsive - give isoproterenol 2–10 mcg/min infusion or pacing to a rate of 100–120 depolarizations/minute as required to suppress PVC, usually terminates Torsade de Pointes	-

Tisdale JE, et al. Circ Cardiovasc Qual Outcomes 2013;6:479–87.