Diagnosis and management of short QT syndrome

Establishing a definition of short QT syndrome (SQTS), including symptomatology and QT-interval duration, is still a work in progress. However, it is clear , that SQTS is a rare, life-threatening, inherited heart disease presenting as sudden cardiac death (SCD) or aborted SCD in 34% and a family history of SCD in 15%. Genetic testing is important in diagnosing the disease, but to date a causative mutation is found in <25%. A benign variety of the disease has been observed in children with atrial fibrillation and a KCNH2-V141M mutation, and recently a mutation in the cardiac Cl/HCO₃ exchanger AE3 was found to cause SQTS. Issues related to measuring and correcting the QT interval for heart rate has made it difficult to rely entirely on QT duration for the diagnosis of SQTS. In order to establish the diagnosis on firmer grounds, symptoms, family history, and genetic testing need to be considered. Although the benefit of insertion of an implantable cardioverter-defibrillator as secondary prophylaxis against SCD in a patient with SQTS is well documented, the benefit as primary prophylaxis is controversial and not proven by solid data. In 2 recent similar studies involving 115 patients with approximately 5 years of follow-up, insertion of an implantable cardioverter-defibrillator in 40 patients saved the lives of 12, 11 who had presented with cardiac arrest and 1 with syncope. No appropriate shocks were delivered in any patients who did not have a history of either syncope or cardiac arrest. Currently quinidine is the only drug that has undergone any clinical testing.