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QT-Prolonging Medications and Sudden Death
Study Questions:
What is the relationship between QT-prolonging medications (QTPMs) and arrhythmic and nonarrhythmic sudden cardiac death (SCD)?
Methods:
Autopsies were performed in 525 adult individuals (mean age 61.4, range 18-90 years) with SCD and in 104 control patients with trauma-induced death. The SCDs were classified as sudden arrhythmic death (SAD) or nonarrhythmic (non-SAD) based on the findings at autopsy, toxicologic findings, and detailed review of clinical information. Medication lists were reviewed to identify all QTPMs. The QTPMs were assigned a score of 3 if the risk was established, 2 if the risk was possible, and 1 if the risk was conditional. A total QTPM exposure score was calculated for each patient and classified as none (0), low (1), moderate (2-4), or high (>4). The relationship between QTPM exposure and the cause of SCD was analyzed.
Results:
Patients with SCD were more likely to have had exposure to QTPMs than the control patients (55.4% vs. 26.9%). The use of QTPMs was independently associated with an increased risk of non-SAD in all exposure groups (low: odds ratio [OR], 2.88; moderate risk: OR, 2.62; high: OR, 14.2). QTPMs were not independently associated with the risk of SAD.
Conclusions:
The use of QTPMs is associated with nonarrhythmic causes of SCD, but not SAD.
Perspective:
QTPMs presumably are associated with SCD because QT prolongation can precipitate torsades de pointes. Therefore, the absence of an association between QTPMs and SAD in this study is surprising. A possible problem with the analysis is that the QTc interval near the time of death was not included in the analysis. The presence and extent of QTc prolongation is much more robust than QTPM exposure as an indicator of risk of torsades de pointes.
Clinical Topics: Arrhythmias and Clinical EP, Congenital Heart Disease and Pediatric Cardiology, Prevention, Implantable Devices, EP Basic Science, Genetic Arrhythmic Conditions, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Prevention, CHD and Pediatrics and Quality Improvement
Keywords: Anti-Arrhythmia Agents, Arrhythmias, Cardiac, Autopsy, Death, Sudden, Death, Sudden, Cardiac, Electrocardiography, Long QT Syndrome, Risk Assessment, Secondary Prevention, Torsades de Pointes
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