Proarrhythmic drugs, drug levels, and polypharmacy in victims of sudden arrhythmic death syndrome: An autopsy-based study from Denmark

BACKGROUND Sudden arrhythmic death syndrome (SADS), characterized by an unknown or inconclusive cause of death at autopsy together with a negative or nonlethal toxicology screening result, is the most common cause of sudden cardiac death in victims younger than 35 years. The complete causality of SADS remains unclear, with drugs being a potential risk factor. OBJECTIVE This study aimed to describe the toxicologic profiles of SADS victims, focusing on proarrhythmic drugs, drug levels, and polypharmacy. METHODS All deaths in Denmark of those aged 1-35 years in 2000-2019 and 36-49 years in 2007-2019 were examined through death certificates, national registries, and autopsy reports with toxicology screenings. We investigated all sudden unexpected death victims with an autopsy performed, including negative or nonlethal drug findings, where cause of death was unknown or inconclusive (SADS). RESULTS We identified 477 SADS victims; 313 (66%) had a positive toxicology screening result (adjudicated nonlethal), with an average of 2.8 drugs per case. More than half of the SADS victims with a positive toxicology screening result had QT-prolonging or brugadogenic drugs present. Polypharmacy was present in 66%, psychotropic polypharmacy in 37%, and QT-prolonging polypharmacy in 22%, with the most frequent overall and QT-prolonging drug combination being an antipsychotic and a psychoanaleptic drug. QT-prolonging drugs were more often present at suprapharmacologic levels than non-QT-prolonging drugs. CONCLUSION The majority of the SADS population had a positive toxicology screening result, with a notably large proportion having proarrhythmic drugs and polypharmacy. This highlights the need for future focus on drugs as a risk factor for SADS.