582 Clinical and Genetic Characterisation of Long QT Syndrome in Indigenous Australians

Abstract

There is little data on the clinical and genetic characteristics of long QT syndrome (LQTS) in Indigenous Australians. Here, three Indigenous Australian patients from Central Australia with LQTS are described. Patient 1 is a 38-year-old female who presented feeling generally unwell, with a background of alcohol abuse. No electrolyte abnormalities were detected. Her QTc measurements were 580–625ms. Genetic testing subsequently revealed heterogenicity for a likely pathogenetic variant in KCNQ1, c.1018T>C p.Phe340Leu. Patient 2 is a 21-year-old female who presented with loss of consciousness following seizure-like activity, with a background of suspected seizures and alcohol abuse. QTc remained intermittently above 500ms despite electrolyte correction. On monitoring, she developed torsades de pointes. Echocardiogram showed a mild dilated cardiomyopathy thought to be alcoholic in aetiology. Genetic testing revealed a variant of uncertain significance in ANK2. Patient 3 is a 39-year-old female who presented with a second episode of polymorphic ventricular tachycardia following excess alcohol consumption, with a background of mild rheumatic valvular disease and alcohol abuse. No family history was suggestive of LQTS. QTc remained elevated above 500ms despite electrolyte correction. Genetic testing is pending. All 3 patients received an implantable cardioverter-defibrillator without complications. This series on LQTS adds significantly to the paucity of data on arrhythmic disorders in Indigenous Australians and highlights the potential importance of exacerbating factors in this population.