Long QT syndrome
Measuring and correcting the QT, congenital LQT1 to LQT3 and their triggers, beta-blockers and ICDs, and acquired QT prolongation from drugs and electrolytes.
Tier 1Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- A long QT reflects delayed ventricular repolarisation. Early afterdepolarisations trigger torsades de pointes, which causes syncope, seizures and sudden death.
- Two groups: congenital LQTS (about 1 in 2,000, mostly KCNQ1, KCNH2 or SCN5A) and acquired QT prolongation from drugs, electrolytes and bradycardia. The second is far commoner on the wards.
- QTc 480 ms or more on repeated ECGs is diagnostic of LQTS when secondary causes are excluded (ESC 2022).
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Sources
- 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;43:3997-4126. doi:10.1093/eurheartj/ehac262European Society of Cardiology, 2022
- Mazzanti A, Maragna R, Vacanti G et al. Interplay between genetic substrate, QTc duration, and arrhythmia risk in patients with long QT syndrome. J Am Coll Cardiol 2018;71:1663-1671Journal of the American College of Cardiology, 2018
- CredibleMeds QTdrugs listAZCERT
- ANZCOR Guideline 11.5: Medications in adult cardiac arrestAU/NZAustralian and New Zealand Committee on Resuscitation, 2025
- Assessing Fitness to Drive for commercial and private vehicle driversAU/NZAustroads and the National Transport Commission, 2022
- Legislation passed to ban the use of adverse genetic testing results in life insuranceAU/NZAustralian Treasury (ministerial media release), 2026
- Last updated
- 14 November 2026
What changed
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