Prescribed drugs and comorbidities as risk factors for Torsades de Pointes arrhythmia: a Swedish population-based...

Drug-induced long QT interval syndrome (LQTS) is a risk for Torsade de Pointes (TdP) arrhythmia. The purpose was to investigate patients diagnosed with TdP in relation to dispensed risk drugs, the presence of comorbidities, and sex-differences.

All patients with a first episode of a registered TdP diagnosis in the National Patient Register between 2006 and 2018 were included in this register-based cohort study. Comorbidities within five years and medications dispensed within 90 days prior to TdP diagnosis were retrieved. Drugs were classified for their risk to cause TdP ("risk drugs") using two different Clinical Decision Support Systems (CredibleMeds and Janusmed).

The cohort consisted of 762 patients (50% females) with TdP, median age 72 years. A majority (59%) were dispensed at least one risk drug and 338 patients (44%) had at least one risk diagnosis for TdP. Concomitant use of several risk drugs was common. Prior to TdP, 558 patients (73%) had at least one risk diagnosis and/or were dispensed at least one risk drug. More females than males used antidepressants (26% vs 12%, p < 0.01) although the total use of risk drugs were similar in females compared to males. More males than females had risk diagnoses for TdP (53% vs. 36%, p < 0.004).

A majority of patients with TdP had been dispensed risk drugs and/or had risk diagnoses. Sex-differences in dispensed drugs and risk diagnoses were identified. Prescription drugs, underlying risk diagnoses and sex should be incorporated into the risk assessment for TdP.