Pediatric Long QT Syndrome Guidelines

Updated: Dec 27, 2020
  • Author: Sreekanth S Raghavan, MBBS, , FACC; Chief Editor: Stuart Berger, MD  more...
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Guidelines Summary


2013 HRS/EHRA/APHRS guidelines

In its 2013 expert consensus statement on inherited primary arrhythmia syndromes, the Heart Rhythm Society/European Heart Rhythm Association/Asia Pacific Heart Rhythm Society (HRS/EHRA/APHRS) recommended a diagnosis of LQTS when any of the following criteria is met [25] :

  • LQTS risk score ≥3.5 in the absence of a secondary cause for QT prolongation and/or
  • Presence of confirmed LQTS gene mutation or
  • QTc (using Bazett formula) ≥500 ms in repeated 12-lead ECGs and in the absence of a secondary cause for QT prolongation.

LQTS can also be diagnosed in the presence of a QTc between 480 and 499 ms in repeated 12-lead ECGs in a patient with unexplained syncope in the absence of a secondary cause for QT prolongation and in the absence of a pathogenic mutation.

2015 ESC guidelines

In 2015, the European Society of Cardiology (ESC) released guidelines for the management of ventricular arrhythmias and the prevention of sudden cardiac death (SCD) which included the following modified recommendation for diagnosis of LQTS  [20] :

LQTS is diagnosed when any of the following criteria is met (class I, level of evidence: C):

  • QTc ≥480 ms in repeated 12-lead ECGs or
  • LQTS risk score >3
  • Presence of confirmed LQTS gene mutation, irrespective of the QT duration.

LQTS should be considered in patients with an unexplained syncopal episode and QTc ≥460 ms in repeated 12-lead ECGs in the absence of secondary causes for QT prolongation (class IIa, level of evidence: C).

Genetic Testing

In 2011, the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA) issued a joint expert consensus statement on genetic testing for channelopathies and cardiomyopathies. Their recommendations for LQTS testing are outlined below. [26]

Comprehensive or LQT1-3 (KCNQ1, KCNH2, and SCN5A) targeted LQTS genetic testing is recommended for:

  • Individuals with a strong clinical index of suspicion for LQTS based on clinical history, family history, and expressed ECG phenotype (class I)
  • Asymptomatic individuals with idiopathic QT prolongation on serial 12-lead ECGs defined as QTc >480 ms (prepuberty) or >500 ms (adults) (class I);
  • May be considered for asymptomatic patients with idiopathic QTc values >460 ms (prepuberty) or >480 ms (adults) on serial 12-lead ECGs (class IIb)

Mutation specific genetic testing is recommended for family members following identification of LQTS mutation in an index case (class I).

Management and Prevention of Sudden Cardiac Death

2015 ESC guidelines 

The following is a summary of recommendation included in the 2015 ESC guidelines for management of of LQTS and preventions of SCD. [20]

Class I  (level of evidence: B)

Lifestyle changes, such as the following:

  • Avoidance of QT-prolonging drugs
  • Correction of electrolyte abnormalities (hypokalemia, hypomagnesemia, hypocalcemia) that may occur during diarrhea, vomiting or metabolic conditions
  • Avoidance of genotype-specific triggers for arrhythmias (strenuous swimming, especially in LQTS1, and exposure to loud noises in LQTS2 patients)

Beta-blockers are recommended for all patients with confirmed LQTS.

ICD implantation is recommended with the use of betablockers for patients LQTS who have had a previous cardiac arrest.

Class IIa 

Consider beta-blockers for carriers of an LQTS genetic mutation and normal QT interval (level of evidence: B).

Consider ICD implantation in addition to beta-blockers in patients with syncope and/or ventricular tachycardia (VT) while receiving an adequate dose of beta-blockers (level of evidence: B).

Left cardiac sympathetic denervation should be considered in patients with symptomatic LQTS when (level of evidence: C):

  • Beta-blockers are ineffective, not tolerated, or contraindicated
  • ICD therapy is contraindicated or refused
  • Patients on beta-blockers with an ICD experience multiple shocks

Class IIb (Level of evidence: C)

Consider sodium channel blockers (mexiletine, flecainide, or ranolazine) as add-on therapy to shorten the QT interval in LQTS3 patients with a QTc >500 ms.

Consider an ICD in addition to beta-blocker therapy in asymptomatic carriers of a pathogenic mutation in KCNH2 or SCN5A when QTc is >500 ms.

Class III (level of evidence: C)

Invasive electrophysiologic study (EPS) with programmed ventricular stimulation (PVS) is not recommended for SCD risk stratification.

2015 AHA/ACC guidelines

A scientific statement published in 2015 by the American Heart Association (AHA) and the American College of Cardiology (ACC) on athletic competition by persons with known or suspected cardiac channelopathies includes the following recommendations related to LQTS [27] :

  • Thorough evaluation of an athlete in whom such a disorder has been diagnosed or is suspected by a heart rhythm specialist or genetic cardiologist experienced in cardiac channelopathies
  • Restriction from all competitive sports for symptomatic athletes with suspected or diagnosed cardiac channelopathy until completion of a comprehensive evaluation, the athlete and family are well informed, implementation of a treatment program, and asymptomatic on therapy for 3 months
  • Asymptomatic athletes who are genotype-positive/phenotype-negative for LQTS, catecholaminergic polymorphic ventricular tachycardia, Brugada syndrome, early repolarization syndrome, short-QT syndrome, or idiopathic ventricular fibrillation may be allowed to take part in all competitive sports if precautionary measures are undertaken (eg, avoidance of QT-prolonging drugs; replenishment of electrolytes/hydration and avoidance of dehydration; avoidance or treatment of hyperthermia from febril illnesses; training-related heat exhaustion or heat stroke; obtaininga personal automatic external defibrillator as part of the athlete's personal sports safety gear; establishment of an emergency plan with appropriate school or team officials)
  • An athlete who is symptomatic for LQTS or in whom it can be found electrocardiographically may be considered for competitive sports (with the exception of competitive swimming, if the athlete is a previously symptomatic LQT1 host) if precautionary measures have been undertaken, treatment is being administered, and the person has been asymptomatic on therapy for at least 3 months (although treatment involving an implantable cardioverter-defibrillator is subject to additional recommendations)