Long QT syndrome

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

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Última revisão: 12 Dec 2025

Última atualização: 29 Aug 2023

Long QT syndrome (LQTS) is characterized by a prolonged QT interval on ECG, which may be congenital or acquired.

In congenital LQTS, genetic mutations affect ion channels important in myocardial repolarization.

Acquired LQTS may occur secondary to ingestion of QT interval-prolonging drugs, electrolyte imbalances, or bradyarrhythmias.

Patients with LQTS are at increased risk of syncope, ventricular arrhythmias (including torsades de pointes), and sudden cardiac death.

Unless there is an identifiable reversible cause, treatment primarily involves lifestyle modification and beta-blocker therapy with the implantation of a cardioverter-defibrillator in selected cases.

Definição

Long QT syndrome (LQTS) is a congenital or acquired condition that is characterized by a prolonged QT interval on the surface ECG and is associated with a high risk of sudden cardiac death due to ventricular tachyarrhythmias. In congenital LQTS, mutations within 17 identified genes result in a variety of channelopathies affecting myocardial repolarization, thus prolonging the QT interval.

Published definitions of the normal QT interval vary. A prolonged QT interval is defined as a heart rate-corrected QT interval (QTc) of >450 ms in males and >460 ms in females.[1]Rautaharju PM, Surawicz B, Gettes LS, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology. Circulation. 2009 Mar 17;119(10):e241-50. The European Society of Cardiology suggests using a QTc of ≥480 ms for diagnosing LQTS and using a QTc of 460-479 as a borderline range where a diagnosis may be considered along with other criteria.[2]

História e exame físico

Principais fatores diagnósticos

history of known gene mutation
use of drugs or circumstances known to increase the QT interval
syncope during heightened adrenergic tones
syncope during arousal or surprise
arrhythmic symptoms postpartum
syncope at rest and during bradycardia
cardiac syncope
palpitations
periodic paralysis
dysmorphic features
sensorineural deafness

Detalhes completos

Outros fatores diagnósticos

dizziness
angina
fatigue
oliguria
muscle weakness
tetany
numbness
Chvostek's sign
Trousseau's sign
cold and pale extremities
hypotension
confusion

Detalhes completos

Fatores de risco

KCNQ1 gene mutations
KCNH2 gene mutations
SCN5A gene mutations
QT interval-prolonging drugs
hypokalemia
hypomagnesemia
hypocalcemia
bradyarrhythmias
central nervous system lesions
female sex
malnutrition

Detalhes completos

Investigações diagnósticas

Primeiras investigações a serem solicitadas

ECG for LQT1
ECG for LQT2
ECG for LQT3
ECG for hypokalemia and hypomagnesemia
ECG for hypocalcemia
ECG for complete atrioventricular (AV) block
serum potassium
serum magnesium
serum calcium

Detalhes completos

Investigações a serem consideradas

Holter monitor
exercise tolerance test
echocardiography
genetic testing
epinephrine test

Detalhes completos

Algoritmo de tratamento

AGUDA

acquired LQTS

congenital LQTS without previous cardiac event

congenital LQTS with previous cardiac event

Colaboradores

Autores

Mehmet K. Aktas, MD, MBA

Associate Professor of Medicine

University of Rochester Medical Center

Rochester

Declarações

MKA declares that he has received research grants from Astra Zeneca, Medtronic, and Boston Scientific. MKA has served as consultant for Abbott and Huxley Medical. MKA holds a patent for "ECG Clock Electrocardiogram Based Diagnostic Device and Method" (US patent #10,085,667). He is the author of a reference cited in this topic.

James P. Daubert, MD

Professor of Medicine

Duke University Medical Center

Duke Clinical Research Institute

Durham

Declarações

JPD declares that he has received honoraria for advisory boards, steering committees, data safety monitoring boards, events committees, and lecture fees from Abbott, Acutus Medical, Affera Inc., Biosense Webster, Biotronik, Boston Scientific, Farapulse, Gilead Sciences Inc., Medtronic, Microport, Phillips, and Vytronus; and research grants from Abbott, Biosense Webster, Boston Scientific, Farapulse, and Medtronic. He receives royalty payments from Wiley, Springboard and McGraw Hill for textbook authorship and educational materials. JPD declares that he has no stock, stock options, or other forms of ownership. He is the author of a reference cited in this topic.

Revisores

Sami Viskin, MD

Director of Cardiac Hospitalization

Department of Cardiology

Tel Aviv Medical Center

Tel Aviv

Israel

Declarações

SV declares that he has no competing interests.

Elizabeth S. Kaufman, MD

Associate Professor

Heart and Vascular Center

MetroHealth Campus

Case Western Reserve University

Cleveland

Declarações

ESK declares that she has no competing interests.

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Referências

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Principais artigos

Zeppenfeld K, Tfelt-Hansen J, de Riva M, et al. 2022 ESC guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2022 Oct 21;43(40):3997-4126.Texto completo Resumo

Priori SG, Wilde AA, Horie M, et al. HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes. Heart Rhythm. 2013 Dec;10(12):1932-63.Texto completo Resumo

Wilde AAM, Semsarian C, Márquez MF, et al. European Heart Rhythm Association (EHRA)/Heart Rhythm Society (HRS)/Asia Pacific Heart Rhythm Society (APHRS)/Latin American Heart Rhythm Society (LAHRS) expert consensus statement on the state of genetic testing for cardiac diseases. Europace. 2022 Sep 1;24(8):1307-67.Texto completo Resumo

Roden DM. Clinical practice. Long-QT syndrome. N Engl J Med. 2008 Jan 10;358(2):169-76. Resumo

Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force on clinical practice guidelines and the Heart Rhythm Society. Circulation. 2018 Sep 25;138(13):e272-391.Texto completo Resumo

Sauer AJ, Moss AJ, McNitt S, et al. Long QT syndrome in adults. J Am Coll Cardiol. 2007 Jan 23;49(3):329-37. Resumo

Schwartz PJ, Moss AJ, Vincent GM, et al. Diagnostic criteria for the long QT syndrome. An update. Circulation. 1993 Aug;88(2):782-4. Resumo

Schwartz PJ, Crotti L. QTc behavior during exercise and genetic testing for the long-QT syndrome. Circulation. 2011 Nov 15;124(20):2181-4.Texto completo Resumo

Artigos de referência

Uma lista completa das fontes referenciadas neste tópico está disponível para os usuários com acesso total ao BMJ Best Practice.

Diagnósticos diferenciais
- Acquired structural heart disease
- Neurocardiogenic (vasovagal) syncope
- Neurologic syncope
Mais Diagnósticos diferenciais
Diretrizes
- European Heart Rhythm Association (EHRA)/Heart Rhythm Society (HRS)/Asia Pacific Heart Rhythm Society (APHRS)/Latin American Heart Rhythm Society (LAHRS) Expert Consensus Statement on the state of genetic testing for cardiac diseases
- 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death
Mais Diretrizes
Folhetos informativos para os pacientes
Heart attack: what is it?
What you can do to prevent another heart attack
Mais Folhetos informativos para os pacientes
Calculadoras
QT Interval Correction
Mais Calculadoras
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Long QT syndrome

Resumo

Definição

História e exame físico

Principais fatores diagnósticos

Outros fatores diagnósticos

Fatores de risco

Investigações diagnósticas

Primeiras investigações a serem solicitadas

Investigações a serem consideradas

Algoritmo de tratamento

acquired LQTS

congenital LQTS without previous cardiac event

congenital LQTS with previous cardiac event

Colaboradores

Autores

Mehmet K. Aktas, MD, MBA

Declarações

James P. Daubert, MD

Declarações

Revisores

Sami Viskin, MD

Declarações

Elizabeth S. Kaufman, MD

Declarações

Créditos aos pareceristas

Declarações

Referências

Principais artigos

Artigos de referência

Uma lista completa das fontes referenciadas neste tópico está disponível para os usuários com acesso total ao BMJ Best Practice.

Diagnósticos diferenciais

Diretrizes

Folhetos informativos para os pacientes

Calculadoras

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice