From the Guidelines
Hydroxychloroquine (Plaquenil) can cause QT interval prolongation, which may lead to symptoms such as dizziness, lightheadedness, fainting, palpitations, irregular heartbeat, and in severe cases, seizures or sudden cardiac arrest, as reported in a 2020 study published in the Journal of the American College of Cardiology 1. The symptoms of QT interval prolongation associated with Plaquenil (hydroxychloroquine) are primarily related to the heart's electrical activity.
- Dizziness and lightheadedness are common symptoms due to the heart's reduced ability to pump blood effectively.
- Fainting or syncope can occur as a result of the heart's inability to maintain a stable rhythm.
- Palpitations and irregular heartbeat are direct consequences of the QT interval prolongation.
- In severe cases, seizures or sudden cardiac arrest may occur, emphasizing the need for immediate medical attention if any of these symptoms are experienced. According to the 2020 study 1, the risk of QT interval prolongation increases with higher doses, longer treatment duration, and in patients with existing heart conditions, electrolyte abnormalities, or when combined with other QT-prolonging medications. Regular electrocardiogram (ECG) monitoring is recommended for high-risk patients, as it allows for the early detection of QT interval prolongation and the implementation of necessary interventions to prevent potentially life-threatening complications 1. It is essential for patients taking Plaquenil to seek immediate medical attention if they experience any symptoms of QT interval prolongation, and not to stop the medication abruptly without consulting their healthcare provider.
From the FDA Drug Label
Hydroxychloroquine sulfate has a potential to prolong the QT interval Ventricular arrhythmias (including torsades de pointes) have been reported in hydroxychloroquine sulfate-treated patients. The magnitude of QT prolongation may increase with increasing concentrations of the drug.
The symptoms of QT interval prolongation associated with Plaquenil (hydroxychloroquine) include ventricular arrhythmias, such as:
- Torsades de pointes Other signs and symptoms of cardiac compromise may occur, including:
- Ventricular hypertrophy
- Pulmonary hypertension
- Conduction disorders, including sick sinus syndrome
- ECG findings, such as atrioventricular, right or left bundle branch block 2
From the Research
QT Interval Prolongation Symptoms
The symptoms of QT interval prolongation associated with Plaquenil (hydroxychloroquine) include:
- Palpitations
- Lightheadedness
- Dizziness
- Syncope (fainting)
- Seizures
- Sudden cardiac arrest
Risk Factors for QT Interval Prolongation
The risk factors for QT interval prolongation include:
- Hypokalemia (low potassium levels)
- Female sex
- Drug-drug interactions
- Advancing age
- Genetic predisposition
- Hypomagnesemia (low magnesium levels)
- Heart failure
- Bradycardia (slow heart rate)
- Use of QT-interval-prolonging drugs, such as hydroxychloroquine 3, 4, 5
Monitoring and Management
Patients at risk for QT interval prolongation should be educated to go directly to the emergency room if they experience any symptoms of QT interval prolongation 3. Close monitoring of the QT interval is recommended for patients receiving hydroxychloroquine, and consideration should be given to patient-specific risk factors for QT interval prolongation 3, 4, 5. Daily electrocardiographic monitoring and other risk mitigation strategies should be considered to prevent possible harms from hydroxychloroquine therapy 5.
QT Interval Prolongation Thresholds
The QTc interval thresholds for considering dose reduction or discontinuation of hydroxychloroquine include:
- QTc interval ≥470 ms for males or ≥480 ms for females
- QTc interval increase of 60 ms or more from pretreatment values
- QTc interval ≥500 ms, in which case the offending drug should be discontinued, and continuous EKG telemetry monitoring should be performed, or the 12-lead EKG should be repeated every 2-4 hours, until the QT interval has normalized 3