Long QT syndrome (LQTS) is a condition affecting repolarization (relaxing) of the heart after a heartbeat, giving rise to an abnormally lengthy QT interval.[7] It results in an increased risk of an irregular heartbeat which can result in fainting, drowning, seizures, or sudden death.[1] These episodes can be triggered by exercise or stress.[6] Some rare forms of LQTS are associated with other symptoms and signs including deafness and periods of muscle weakness.[1]
Long QT syndrome may be present at birth or develop later in life.[1] The inherited form may occur by itself or as part of larger genetic disorder.[1] Onset later in life may result from certain medications, low blood potassium, low blood calcium, or heart failure.[2] Medications that are implicated include certain antiarrhythmics, antibiotics, and antipsychotics.[2] LQTS can be diagnosed using an electrocardiogram (EKG) if a corrected QT interval of greater than 450–500 milliseconds is found, but clinical findings, other EKG features, and genetic testing may confirm the diagnosis with shorter QT intervals.[4][5][8]
Management may include avoiding strenuous exercise, getting sufficient potassium in the diet, the use of beta blockers, or an implantable cardiac defibrillator.[6] For people with LQTS who survive cardiac arrest and remain untreated, the risk of death within 15 years is greater than 50%.[9][6] With proper treatment this decreases to less than 1% over 20 years.[3]
Long QT syndrome is estimated to affect 1 in 7,000 people.[6] Females are affected more often than males.[6] Most people with the condition develop symptoms before they are 40 years old.[6] It is a relatively common cause of sudden death along with Brugada syndrome and arrhythmogenic right ventricular dysplasia.[3] In the United States it results in about 3,500 deaths a year.[6] The condition was first clearly described in 1957.[10]
^ abcdef"Long QT syndrome". Genetic and Rare Diseases Information Center (GARD) – an NCATS Program. 2017. Retrieved 14 December 2017.
^ abcMorita H, Wu J, Zipes DP (August 2008). "The QT syndromes: long and short". Lancet. 372 (9640): 750–63. doi:10.1016/S0140-6736(08)61307-0. PMID 18761222. S2CID 41181673.
^ abcdFerri FF (2016). Ferri's Clinical Advisor 2017 E-Book: 5 Books in 1. Elsevier Health Sciences. p. 736. ISBN 9780323448383.
^ abCite error: The named reference ESC 2015 was invoked but never defined (see the help page).
^ abCite error: The named reference HRS guidelines was invoked but never defined (see the help page).
^ abcdefghij"Long QT Syndrome". NHLBI, NIH. Retrieved 14 December 2017.
^Levine E, Rosero SZ, Budzikowski AS, Moss AJ, Zareba W, Daubert JP (August 2008). "Congenital long QT syndrome: considerations for primary care physicians". Cleveland Clinic Journal of Medicine. 75 (8): 591–600. doi:10.3949/ccjm.75.8.591. PMID 18756841. S2CID 4237579.
^Afzal, Muhammad Adil; Khalid, Noman; Abdullah, Muhammad; ul-Haiy, Ata; Michael, Patrick (2023). "Hydroxyzine-Induced Torsade De Pointes: A Case Report and a Literature Review". Cureus. 15 (7): e41588. doi:10.7759/cureus.41588. ISSN 2168-8184. PMC 10407684. PMID 37559846.
^Ackerman MJ, Priori SG, Dubin AM, Kowey P, Linker NJ, Slotwiner D, et al. (January 2017). "Beta-blocker therapy for long QT syndrome and catecholaminergic polymorphic ventricular tachycardia: Are all beta-blockers equivalent?". Heart Rhythm. 14 (1): e41–e44. doi:10.1016/j.hrthm.2016.09.012. PMID 27659101. Among patients who have experienced a LQTS-triggered cardiac event (arrhythmic syncope, arrhythmic syncope followed by seizures, or aborted cardiac arrest), the untreated natural history is grim, with >50% mortality at 15 years.
^Vincent JL, Abraham E, Kochanek P, Moore FA, Fink MP (2011). Textbook of Critical Care E-Book. Elsevier Health Sciences. p. 578. ISBN 978-1437715682.
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