Short QT Syndrome
Short QT Syndrome (SQTS) is a rare form of channelopathy with a moderately high risk of SCD, but the syndrome is not well-defined and information about long term follow-up still very scarce. A short QT interval is the main component of the syndrome, but b
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Abstract
Short QT Syndrome (SQTS) is a rare form of channelopathy with a moderately high risk of SCD, but the syndrome is not well-defined and information about long term follow-up still very scarce. A short QT interval is the main component of the syndrome, but because of an abnormal relationship between the QT interval and the RR interval in SQTS patients, the short QT interval in such patients is often only apparent at heart rates close to 60 bpm. Since routine ECGs are often taken at heart rates faster than that, many patients with SQTS may be missed. Many mutations have been found responsible for SQTS, but in published families a mutation has only been found in one of every four, who has been genetically tested. Most diagnoses are therefore based upon the clinical presentation, which in 90 % of the cases has included a family member with SCD. The treatment of choice is an implantable defibrillator. Keywords
Short QT interval • Short QT syndrome • Sudden cardiac death • Cardiac channelopathies • Potassium channel mutations • Atrial fibrillation • Implantable defibrillators
Introduction Since the discovery of Short QT Syndrome (SQTS) less than 12 years ago [1], a lot have been learned about the latest member of the so-called P. Bjerregaard, MD, DMSc (*) Division of Cardiology, VA Medical Center, Washington University in St. Louis, 915 North Grand, St. Louis, MO 63106, USA e-mail: [email protected] I. Gussak, MD, PhD, FACC Ono Pharmaceutical USA, Lawrenceville, NJ, USA Department of Internal Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick, NJ, USA
e-mail: [email protected]
channelopathies, mainly from case reports and research in a few laboratories and clinical centers especially dedicated to this syndrome. Despite the fact that the total number of published cases has just reached 100, the most important aspects of the syndrome have by now been investigated, latest by the addition of a clinical follow-up study of patients with SQTS (Table 33.1) [2–18]. The population of patients with SQTS will continue to grow as evidenced by the fact, that the first patient found with the syndrome has recently given birth to a child, who also has the syndrome. Most impressive is the list of mutations that has been found, in some cases in only a single individual, and the functional testing of these mutations in patch-clamp experiments and in silico has greatly improved
I. Gussak, C. Antzelevitch (eds.), Electrical Diseases of the Heart, DOI 10.1007/978-1-4471-4881-4_33, © Springer-Verlag London 2013
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TABLE 33–1. Time table for “First Time Events” in the short history of short QT syndrome 1999 2000 2003 2004
2005
2006 2007
2008 2009 2011
Discovery of family with SQTS (Bjerregaard P, 1999, personal communication) Paper describing SQTS (Gussak et al. [1]) High incidence of SCD in families with SQTS (Gaita et al. [2]) ICD treatment of patients with SQTS (Schrimpf et al. [3]) Mutation found in families with SQ
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