Atenolol reduces cardiac-mediated mortality in genetic mouse model of sudden unexpected death in epilepsy

Sudden Unexpected Death in Epilepsy (SUDEP) is the leading cause of premature mortality in epilepsy. Genetic cardiac risk factors, including loss-of-function KCNH2 variants, have been linked to SUDEP. We hypothesised that seizures and LQTS interact to increase SUDEP risk. To investigate this, we crossed Kcnh2 +/- and Gabrg2 R43Q/+ mice that model LQTS and genetic epilepsy, respectively. Electrocorticography and electrocardiogram confirmed that Kcnh2 +/- mice had a LQTS phenotype, while Gabrg2 R43Q/+ mice displayed spontaneous seizures. Double mutant mice ( Gabrg2 R43Q/+/ Kcnh2 +/-) had both seizure and LQTS phenotypes that were indistinguishable from the respective single mutant mice. Survival analysis revealed that Gabrg2 R43Q/+/ Kcnh2 +/- mice experienced a disproportionate higher rate of seizure-related death. Long-term oral administration of atenolol, a cardiac-selective β-blocker, significantly improved survival in the Gabrg2 R43Q/+/ Kcnh2 +/- mice. An additional mouse model, Hcn1M294L /+/ Kcnh2 +/-, based on a HCN1 developmental epileptic encephalopathy variant, also experienced a disproportionately higher rate of premature death that was rescued by atenolol. Kcnh2 +/- mice also spent more time in ventricular arrhythmia during proconvulsant-induced seizures. Overall, the data implicates cardiac and loss-of-function KCNH2 variants as an important risk factor, and the potential repurposing of β- blockers as a prevention strategy, for SUDEP in a subset of epilepsy patients. ### Competing Interest Statement SFB declares unrestricted educational grants from UCB Pharma, SciGen and Eisai and consultancy fees from Praxis Precision Medicines. IES has served on scientific advisory boards for BioMarin, Chiesi, Eisai, Encoded Therapeutics, GlaxoSmithKline, Knopp Biosciences, Nutricia, Rogcon, Takeda Pharmaceuticals, UCB, Xenon Pharmaceuticals, Cerecin; has received speaker honoraria from GlaxoSmithKline, UCB, BioMarin, Biocodex, Chiesi, Liva Nova, Nutricia, Zuellig Pharma, Stoke Therapeutics and Eisai; has received funding for travel from UCB, Biocodex, GlaxoSmithKline, Biomarin, Encoded Therapeutics, Stoke Therapeutics and Eisai; has served as an investigator for Anavex Life Sciences, Cerevel Therapeutics, Eisai, Encoded Therapeutics, EpiMinder Inc, Epygenyx, ES-Therapeutics, GW Pharma, Marinus, Neurocrine BioSciences, Ovid Therapeutics, Takeda Pharmaceuticals, UCB, Ultragenyx, Xenon Pharmaceuticals, Zogenix and Zynerba; and has consulted for Care Beyond Diagnosis, Epilepsy Consortium, Atheneum Partners, Ovid Therapeutics, UCB, Zynerba Pharmaceuticals, BioMarin, Encoded Therapeutics and Biohaven Pharmaceuticals; and is a Non-Executive Director of Bellberry Ltd and a Director of the Australian Academy of Health and Medical Sciences and the Australian Council of Learned Academies Limited. She may accrue future revenue on pending patent WO61/010176 (filed: 2008): Therapeutic Compound; has a patent for SCN1A testing held by Bionomics Inc and licensed to various diagnostic companies; has a patent molecular diagnostic/theranostic target for benign familial infantile epilepsy (BFIE) [PRRT2] 2011904493 & 2012900190 and PCT/AU2012/001321 (TECH ID:2012-009). The remaining authors have no competing interests.