Medications that Prolong the QT Interval

Introduction to QT Interval Prolongation

• The American College of Cardiology notes that both quetiapine and sertralina can prolong the QT interval, with quetiapine having a higher risk of significant QT prolongation than sertralina 1, 2

Medications Associated with QT Interval Prolongation

• The European Heart Journal reports that antipsychotics have different degrees of risk for prolonging the QT interval, with quetiapine associated with a moderate risk (approximately 6 ms) 3
• The Journal of the American College of Cardiology states that sertralina is identified as a medication that can prolong the QT interval, although with a lower risk than many antipsychotics 2
• The European Heart Journal notes that selective serotonin reuptake inhibitors (SSRIs) like sertralina have a lower risk of QT prolongation than tricyclic antidepressants 1
• The Journal of the American College of Cardiology lists other antidepressants that prolong the QT interval, including escitalopram, venlafaxina, and mirtazapina 2
• The Thorax journal reports that antiemetics (domperidona, metoclopramida, 5HT3 antagonists) can also prolong the QT interval 4, 2
• The Circulation journal notes that metadona can prolong the QT interval 5
• The Journal of the American College of Cardiology states that certain anticancer agents (arsenic trioxide, tyrosine kinase inhibitors) can also prolong the QT interval 6

Risk Factors for QT Interval Prolongation and Torsades de Pointes

• The Circulation journal identifies risk factors for QT interval prolongation, including advanced age, female sex, cardiac disease, slow heart rate, electrolyte disturbances, starvation, and acquired or genetic metabolic disorders 7

Recommendations for Management

• The European Heart Journal recommends adjusting the dose or interrupting the medication when the QTc interval reaches a duration >500 ms or increases >60 ms compared to the baseline value 1
• The Journal of the American College of Cardiology recommends monitoring plasma potassium levels to avoid hypokalemia during antipsychotic treatment 1
• The European Heart Journal advises against treating with more than one medication that prolongs the QT interval 1
• The Journal of the American College of Cardiology recommends evaluating the QT interval before starting treatment and during dose titration with antipsychotics 1
• The Journal of the American College of Cardiology suggests performing a baseline ECG in all patients and correcting electrolyte abnormalities before starting treatment 2
• The Journal of the American College of Cardiology recommends repeating the ECG 7 days after starting therapy and after any dose change 2
• The Journal of the American College of Cardiology advises suspending treatment if the QTc is >500 ms during monitoring 2

Management of Torsades de Pointes

• The Journal of the American College of Cardiology recommends administering 2g of magnesium IV as the initial drug of choice, regardless of serum magnesium level 2
• The Journal of the American College of Cardiology suggests that non-synchronized defibrillation may be indicated 2
• The Journal of the American College of Cardiology notes that overdrive pacing (with short-term pacemaker rates of 90-110 ms) can be useful for shortening the QTc 2
• The Journal of the American College of Cardiology recommends isoproterenol IV titrated to heart rates >90 ms when a temporary pacemaker is not immediately available 2
• The Journal of the American College of Cardiology advises correcting all electrolyte abnormalities and suspending medications that prolong the QT interval 2

Risco de Prolongamento do Intervalo QT com Domperidona e Clorpromazina

Mecanismo de Risco

• A combinação de domperidona e clorpromazina 100mg/dia apresenta um risco significativo de prolongamento do intervalo QT, podendo levar a arritmias ventriculares potencialmente fatais, e esta combinação deve ser evitada sempre que possível, de acordo com a British Thoracic Society 8
• Tanto a domperidona quanto a clorpromazina são medicamentos conhecidos por prolongarem o intervalo QT individualmente 8

Evidências de Risco

• A British Thoracic Society especificamente lista antipsicóticos (incluindo clorpromazina) e antieméticos (incluindo domperidona) como medicamentos que aumentam o risco de prolongamento do QT quando usados juntos 8, 9

Fatores de Risco Adicionais

• Pacientes com doença cardíaca pré-existente, idade avançada, sexo feminino e bradicardia têm risco aumentado de complicações arrítmicas, de acordo com o European Heart Journal 10

Recomendações de Monitoramento

• Monitorar eletrólitos (potássio, magnésio, cálcio) antes e periodicamente durante o tratamento com domperidona e clorpromazina 8
• Suspender o tratamento se o QTc exceder 500 ms ou aumentar >60 ms em relação ao valor basal, de acordo com o European Heart Journal 10

Manejo de Complicações

• Se ocorrer síncope, obter um ECG imediatamente para detectar prolongamento do QT, e descontinuar ambos os medicamentos se o paciente desenvolver arritmia ventricular clinicamente significativa ou um intervalo QTc >500 ms (confirmado por ECG repetido) 8

Metoclopramide and QT Interval Prolongation

Risk Factors and Clinical Monitoring

• The American Heart Association, as published in Circulation, recommends monitoring QT interval during treatment with metoclopramide, especially when combined with other QT-prolonging medications, in patients with risk factors such as female gender, advanced age, heart disease, bradycardia, and genetic predisposition to QT prolongation 11
• The American Heart Association, as published in Circulation, suggests documenting QTc in the patient's medical record using rhythm strip examples before drug initiation and at least every 8 hours in high-risk situations, and correcting any electrolyte abnormalities immediately 11

Relative Risk Compared to Other Medications

• Metoclopramide appears to have a lower risk of QT prolongation than high-risk medications like antiarrhythmic agents, methadone, thioridazine, and haloperidol, according to the American Heart Association, as published in Circulation 12, 13