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Long QT syndrome

Key sources
The following summarized guidelines for the evaluation and management of longQT syndrome are prepared by our editorial team based on guidelines from the Global Initiative for Asthma (GINA 2023), the European Society of Cardiology (ESC 2022; 2018), the American Heart Association (AHA 2020), the American Academy of Neurology (AAN 2019), the American Heart Association (AHA/HRS/ACC 2018), the Asia Pacific Heart Rhythm Society (APHRS/EHRA/HRS 2013), and the European Heart Rhythm Association (EHRA/HRS 2011).


1.Screening and diagnosis

Diagnostic criteria: as per ESC 2022 guidelines, diagnose longQT syndrome with either QTc ≥ 480 ms in repeated 12-lead ECGs with or without symptoms or longQT syndrome diagnostic score > 3.
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2.Classification and risk stratification

Risk assessment: as per ESC 2022 guidelines, consider calculating the arrhythmic risk before initiation of therapy based on the genotype and duration of QTc interval in patients with longQT syndrome.

3.Diagnostic investigations

Electrocardiogram: consider obtaining ambulatory ECG monitoring, exercise treadmill testing, and/or recording the ECG lying and immediately on standing for establishing a diagnosis and monitoring the response to therapy in patients with suspected longQT syndrome.

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  • Epinephrine challenge testing

  • Genetic testing

4.Diagnostic procedures

Electrophysiology study: as per ESC 2022 guidelines, do not obtain invasive electrophysiologic testing in patients with longQT syndrome.

5.Medical management

Avoidance of triggers/aggravators: as per GINA 2023 guidelines, obtain an ECG for long QTc before initiating long-term azithromycin in patients with persistent symptomatic asthma, and reassess after a month on treatment.

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  • Beta-blockers

  • Sodium channel blockers

  • Intravenous magnesium

6.Therapeutic procedures

Implantable cardioverter-defibrillator: as per ESC 2022 guidelines, perform ICD placement in addition to β-blockers in patients with longQT syndrome in cardiac arrest.
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7.Surgical interventions

Left cardiac sympathetic denervation
As per ESC 2022 guidelines:
Perform left cardiac sympathetic denervation in patients with symptomatic long QT syndrome when:
ICD therapy is contraindicated or declined
patient is on β-blockers and genotype-specific drugs with an ICD and experiences multiple shocks or syncope due to ventricular arrhythmia
Consider performing either ICD placement or left cardiac sympathetic denervation in patients with symptomatic long QT syndrome when β-blockers and genotype-specific therapies are not tolerated or contraindicated at therapeutic doses.