Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

acquired LQTS

1st line – removal or treatment of causative factor(s)

Back
ACUTE
|
acquired LQTS
1st line – 

removal or treatment of causative factor(s)

In acquired LQTS, management involves thorough assessment in order to identify and remove or treat the causative factor.

Take a drug history to identify and remove drugs known to prolong the QT interval or cause depletion of potassium and/or magnesium.[21][22] Credible Meds (Arizona CERT): drugs that prolong the QT interval Opens in new window​ Consult a drug formulary for a full list of drugs that prolong the QT interval.

Measure serum electrolytes and correct hypokalaemia, hypomagnesaemia, and hypocalcaemia; the goals of therapy include achieving a 'high normal' potassium (of at least 4.0 to 4.5 mEq).

Follow-up serial, periodic ECG monitoring until QT interval has normalised.

Any sudden bradycardia or atrioventricular (AV) nodal block may result in QT prolongation or pause-dependent QT prolongation. If an identifiable cause is not present, treatment involves implantation of a pacemaker (temporary if the bradycardia or AV block improves, permanent if symptomatic bradycardia or AV block persists).

Prophylactic treatment with beta-blockers and lifestyle modification are not indicated in these patients if the QT-prolonging agent is identified and removed.

Cardiac events may include syncope, ventricular tachyarrhythmias, torsades de pointes, or cardiac arrest. For details of management, see Sustained ventricular tachycardias and Cardiac arrest.

Consider – beta-blocker, lifestyle modification, and monitoring

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ACUTE
|
acquired LQTS
Consider – 

beta-blocker, lifestyle modification, and monitoring

Additional treatment recommended for SOME patients in selected patient group

Beta-blockers and lifestyle modifications may be indicated if removal of the causative drug is not possible due to medical necessity.

Ideally non-selective beta-blockers (e.g., nadolol, propranolol) are used.[2]

As ventricular arrhythmias may arise during a state of high adrenergic tone, particularly increasing the occurrence of afterdepolarisations, beta-blockers are used to blunt adrenergic stimulation. Beta-blockers themselves do not shorten the QT interval, but their use is thought to prevent ventricular tachyarrhythmias.

Low-dose beta-blockers are prescribed initially and titrated up as tolerated.

Dose adjustments may be required to avoid symptomatic bradycardia.

Electrolyte loss due to vomiting, diarrhoea, or excessive sweating should be replaced with electrolyte solutions.

Sympathomimetics, factors that may prolong the QT interval, and startling acoustic stimulation such as alarm clocks should be avoided.

Generally, competitive sports and extreme exertion should be avoided. However, patients who wish to engage in competitive sports should be referred for expert evaluation for risk stratification.[3] Selected low-risk patients without a history of exercise-induced symptoms may be considered for sports participation in consultation with an expert in LQTS and with careful education and consideration of options.[51]

ECG should be monitored annually or bi-annually and after initiation or adjustment of beta-blocker therapy (if applicable).

Exercise testing and/or holter monitoring should be carried out to confirm adequate beta-blockade after the initiation of beta-blockers, assess ongoing adequacy of beta-blockade, and augment dosage as necessary in children undergoing somatic growth (if applicable).

Measure serum electrolytes to monitor for hypokalaemia, hypomagnesaemia, and hypocalcaemia.

Review medication for drugs contraindicated in LQTS.

Consult a drug formulary for a full list of drugs that prolong the QT interval.

Take symptom history for detection of interim syncope.

Primary options

nadolol: adults: 40 mg orally once daily initially, increase according to response, maximum 320 mg/day

OR

propranolol: neonates: consult specialist for guidance on dose; children: 1 mg/kg/day orally (immediate-release) given in 3 divided doses initially, increase according to response, maximum 8 mg/kg/day; adults: 30-160 mg/day orally (immediate-release) given in 3 divided doses

congenital LQTS without previous cardiac event

1st line – lifestyle modification and monitoring

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ACUTE
|
congenital LQTS without previous cardiac event
|
low risk
1st line – 

lifestyle modification and monitoring

Cardiac events may include syncope, ventricular tachyarrhythmias, torsades de pointes, or cardiac arrest.

Low risk: corrected QT interval (QTc) <500 ms in men or women with LQT1 and LQT2, women with LQT3.

Electrolyte loss due to vomiting, diarrhoea, or excessive sweating should be replaced with electrolyte solutions. Patients with LQT2 particularly require adequate potassium levels, and oral supplementation may be beneficial.[5]

Sympathomimetics, factors that may prolong the QT interval, and startling acoustic stimulation such as alarm clocks should be avoided (especially for LQT2 patients).

Generally, competitive sports and extreme exertion should be avoided, and non-competitive swimming (especially for LQT1 patients) should be limited and done under close supervision. However, patients who wish to engage in competitive sports should be referred for expert evaluation for risk stratification.[3] Selected low-risk patients without a history of exercise-induced symptoms may be considered for sports participation in consultation with an expert in LQTS and with careful education and consideration of options.[51]

ECG should be monitored annually or bi-annually and after initiation or adjustment of beta-blocker therapy (if applicable).

Exercise testing and/or holter monitoring should be carried out to confirm adequate beta-blockade after the initiation of beta-blockers (if applicable), assess ongoing adequacy of beta-blockade, and augment dosage as necessary in children undergoing somatic growth (if applicable).

Measure serum electrolytes to monitor for hypokalaemia, hypomagnesaemia, and hypocalcaemia.

Review medication for drugs contraindicated in LQTS.

Consult a drug formulary for a full list of drugs that prolong the QT interval.

Take symptom history for detection of interim syncope.

Plus – beta-blocker

Back
ACUTE
|
congenital LQTS without previous cardiac event
|
low risk
Plus – 

beta-blocker

Treatment recommended for ALL patients in selected patient group

Cardiac events may include syncope, ventricular tachyarrhythmias, torsades de pointes, or cardiac arrest.

The mainstay of medical treatment for all patients with LQTS is beta-blocker therapy, ideally non-selective beta-blockers (e.g., nadolol, propranolol).[2] As ventricular arrhythmias may arise during a state of high adrenergic tone, particularly increasing the occurrence of afterdepolarisations, beta-blockers are used to blunt adrenergic stimulation. Beta-blockers themselves do not shorten the QT interval, but their use is thought to prevent ventricular tachyarrhythmias.

Low risk: corrected QT interval (QTc) <500 ms in men or women with LQT1 and LQT2, women with LQT3.

There is some debate concerning the administration of beta-blockers to patients with LQT3 verified by genotyping. Data from one study show that beta-blocker therapy reduces the risk of life-threatening cardiac events in females with LQT3; however, efficacy in males could not be determined conclusively because of the low number of events.[52]

Beta-blocker therapy should also be considered in patients with a normal QTc interval in the presence of a pathogenic mutation.[2]

Low-dose beta-blockers are prescribed initially and titrated up as tolerated.

Dose adjustments may be required to avoid symptomatic bradycardia.

Primary options

nadolol: adults: 40 mg orally once daily initially, increase according to response, maximum 320 mg/day

OR

propranolol: neonates: consult specialist for guidance on dose; children: 1 mg/kg/day orally (immediate-release) given in 3 divided doses initially, increase according to response, maximum 8 mg/kg/day; adults: 30-160 mg/day orally (immediate-release) given in 3 divided doses

1st line – lifestyle modification and monitoring

Back
ACUTE
|
congenital LQTS without previous cardiac event
|
high risk
1st line – 

lifestyle modification and monitoring

Cardiac events may include syncope, ventricular tachyarrhythmias, torsades de pointes, or cardiac arrest.

High risk: corrected QT interval (QTc) >500 ms in men or women with LQT1 and LQT2 and in men with LQT3, and QTc >550 ms.

Electrolyte loss due to vomiting, diarrhoea, or excessive sweating should be replaced with electrolyte solutions. Patients with LQT2 particularly require adequate potassium levels, and oral supplementation may be beneficial.[5]

Sympathomimetics, factors that may prolong the QT interval, and startling acoustic stimulation such as alarm clocks should be avoided (especially for LQT2 patients).

Generally, competitive sports and extreme exertion should be avoided, and non-competitive swimming (especially for LQT1 patients) should be limited and done under close supervision. However, patients who wish to engage in competitive sports should be referred for expert evaluation for risk stratification.[3]

ECG should be monitored annually or bi-annually and after initiation or adjustment of beta-blocker therapy (if applicable).

Exercise testing and/or holter monitoring should be carried out to confirm adequate beta-blockade after the initiation of beta-blockers (if applicable), assess ongoing adequacy of beta-blockade, and augment dosage as necessary in children undergoing somatic growth (if applicable).

Measure serum electrolytes to monitor for hypokalaemia, hypomagnesaemia, and hypocalcaemia.

Review medication for drugs contraindicated in LQTS.

Consult a drug formulary for a full list of drugs that prolong the QT interval.

Take symptom history for detection of interim syncope.

Plus – beta-blocker

Back
ACUTE
|
congenital LQTS without previous cardiac event
|
high risk
Plus – 

beta-blocker

Treatment recommended for ALL patients in selected patient group

Cardiac events may include syncope, ventricular tachyarrhythmias, torsades de pointes, or cardiac arrest. The mainstay of medical treatment for all patients with LQTS is beta-blocker therapy, ideally non-selective beta-blockers (e.g., nadolol, propranolol).[2]

As ventricular arrhythmias may arise during a state of high adrenergic tone, particularly increasing the occurrence of afterdepolarisations, beta-blockers are used to blunt adrenergic stimulation. Beta-blockers themselves do not shorten the QT interval, but their use is thought to prevent ventricular tachyarrhythmias.

High risk: corrected QT interval (QTc) >500 ms in men or women with LQT1 and LQT2 and in men with LQT3 and QTc >550 ms.

There is some debate concerning the administration of beta-blockers to patients with LQT3 verified by genotyping. Data from one study show that beta-blocker therapy reduces the risk of life-threatening cardiac events in females with LQT3; however, efficacy in males could not be determined conclusively because of the low number of events.[52] 

Low-dose beta-blockers are prescribed initially and titrated up as tolerated.

Dose adjustments may be required to avoid symptomatic bradycardia.

Primary options

nadolol: adults: 40 mg orally once daily initially, increase according to response, maximum 320 mg/day

OR

propranolol: neonates: consult specialist for guidance on dose; children: 1 mg/kg/day orally (immediate-release) given in 3 divided doses initially, increase according to response, maximum 8 mg/kg/day; adults: 30-160 mg/day orally (immediate-release) given in 3 divided doses

Consider – left cardiac sympathetic denervation

Back
ACUTE
|
congenital LQTS without previous cardiac event
|
high risk
Consider – 

left cardiac sympathetic denervation

Additional treatment recommended for SOME patients in selected patient group

May be considered in patients with recurrent syncope despite treatment with beta-blockers or in those requiring multiple appropriate ICD shocks. It may also be an option in patients who are deemed not to be ideal candidates for an ICD, such as children, due to the physical limitations of age and height and the psychological distress of ICD shocks.

Consider – implantable cardioverter-defibrillator (ICD)

Back
ACUTE
|
congenital LQTS without previous cardiac event
|
high risk
Consider – 

implantable cardioverter-defibrillator (ICD)

Additional treatment recommended for SOME patients in selected patient group

Cardiac events may include syncope, ventricular tachyarrhythmias, torsades de pointes, or cardiac arrest.

In Jervell and Lange-Nielsen syndrome patients, and in certain very high-risk patients with LQT1, LQT2, or LQT3, ICD can be considered but expert consultation should be sought first.[2]​ This should include a discussion with the patient regarding the risks of not having an ICD and the advantages and disadvantages of an ICD.

Single- or dual-chamber depending on the individual patient and following specialist (cardiologist or electrophysiologist) advice.

Consider – mexiletine

Back
ACUTE
|
congenital LQTS without previous cardiac event
|
high risk
Consider – 

mexiletine

Additional treatment recommended for SOME patients in selected patient group

Should be considered in patients with confirmed LQT3, especially those with syncope or ICD shocks despite beta-blocker therapy; use in other genotypes is being investigated.[5][54][55]​​​

Oral testing should be carried out to ensure that the QTc is shortened by at least 40 ms before prescribing mexiletine long term.[2] There is currently no evidence on whether mexiletine should be given alone or in combination with beta-blocker therapy for patients with LQT3.[2]

Primary options

mexiletine: consult specialist for guidance on dose

congenital LQTS with previous cardiac event

1st line – beta-blocker

Back
ACUTE
|
congenital LQTS with previous cardiac event
1st line – 

beta-blocker

Cardiac events may include syncope, ventricular tachyarrhythmias, torsades de pointes, or cardiac arrest.

The mainstay of medical treatment for all patients with LQTS is beta-blocker therapy, ideally non-selective beta-blockers (e.g., nadolol, propranolol).[2]​ As ventricular arrhythmias may arise during a state of high adrenergic tone, particularly increasing the occurrence of afterdepolarisations, beta-blockers are used to blunt adrenergic stimulation. Beta-blockers themselves do not shorten the QT interval, but their use is thought to prevent ventricular tachyarrhythmias.

Low-dose beta-blockers are prescribed initially and titrated up as tolerated.

Dose adjustments may be required to avoid symptomatic bradycardia.

Primary options

nadolol: adults: 40 mg orally once daily initially, increase according to response, maximum 320 mg/day

OR

propranolol: neonates: consult specialist for guidance on dose; children: 1 mg/kg/day orally (immediate-release) given in 3 divided doses initially, increase according to response, maximum 8 mg/kg/day; adults: 30-160 mg/day orally (immediate-release) given in 3 divided doses

Plus – lifestyle modification and monitoring

Back
ACUTE
|
congenital LQTS with previous cardiac event
Plus – 

lifestyle modification and monitoring

Treatment recommended for ALL patients in selected patient group

Cardiac events may include syncope, ventricular tachyarrhythmias, torsades de pointes, or cardiac arrest.

Electrolyte loss due to vomiting, diarrhoea, or excessive sweating should be replaced with electrolyte solutions. Patients with LQT2 particularly require adequate potassium levels, and oral supplementation may be beneficial.[5]

Sympathomimetics, factors that may prolong the QT interval, and startling acoustic stimulation such as alarm clocks should be avoided (especially for LQT2 patients).

Generally, competitive sports and extreme exertion should be avoided, and non-competitive swimming (especially for LQT1 patients) should be limited and done under close supervision. However, patients who wish to engage in competitive sports should be referred for expert evaluation for risk stratification.[3] Selected low-risk patients without a history of exercise-induced symptoms may be considered for sports participation in consultation with an expert in LQTS and with careful education and consideration of options.[51]

ECG should be monitored annually or bi-annually and after initiation or adjustment of beta-blocker therapy (if applicable).

Exercise testing and/or holter monitoring should be carried out to confirm adequate beta-blockade after the initiation of beta-blockers (if applicable), assess ongoing adequacy of beta-blockade, and augment dosage as necessary in children undergoing somatic growth (if applicable).

Measure serum electrolytes to monitor for hypokalaemia, hypomagnesaemia, and hypocalcaemia.

Review medication for drugs contraindicated in LQTS.

Consult a drug formulary for a full list of drugs that prolong the QT interval.

Take symptom history for detection of interim syncope.

Consider – implantable cardioverter-defibrillator (ICD)

Back
ACUTE
|
congenital LQTS with previous cardiac event
Consider – 

implantable cardioverter-defibrillator (ICD)

Additional treatment recommended for SOME patients in selected patient group

Use of an ICD, in conjunction with beta-blockers, has proven invaluable in the treatment of patients with LQTS who have recurrent arrhythmic syncope or documented torsades de pointes despite optimally dosed beta-blocker therapy.[2][56][57]​​​

Indications for an ICD include any of the following: previous ventricular tachyarrhythmias and/or torsades de pointes, previous cardiac arrest, persistent syncope, some patients with high-risk LQTS, especially patients with LQT2 or those with multiple mutations, contraindications or intolerance to beta-blockers.[2][58]

Single- or dual-chamber depending on the individual patient and following specialist (cardiologist or electrophysiologist) advice.

Consider – mexiletine

Back
ACUTE
|
congenital LQTS with previous cardiac event
Consider – 

mexiletine

Additional treatment recommended for SOME patients in selected patient group

Should be considered in patients with confirmed LQT3, especially those with syncope or ICD shocks despite beta-blocker therapy; use in other genotypes is being investigated.[2][5][54][55]​​​​

Primary options

mexiletine: consult specialist for guidance on dose

2nd line – left cardiac sympathetic denervation

Back
ACUTE
|
congenital LQTS with previous cardiac event
2nd line – 

left cardiac sympathetic denervation

Sometimes called stellate ganglionectomy, this procedure involves surgical resection of the lower half of the left stellate ganglion along with several other thoracic ganglia (T2 to T4) in an attempt to partially denervate the heart.

Indications include inadequate response to or not a candidate for implantable cardioverter-defibrillator (ICD), receipt of multiple ICD shocks, and children in whom an ICD is not appropriate due to the physical limitations of age and height and the psychological distress of ICD shocks.[2]

A thoracoscopic left cardiac sympathetic denervation has been developed, and is now routinely done by experienced surgeons in specialised medical centres.

Plus – continue beta-blocker, lifestyle modification, and monitoring

Back
ACUTE
|
congenital LQTS with previous cardiac event
Plus – 

continue beta-blocker, lifestyle modification, and monitoring

Treatment recommended for ALL patients in selected patient group

Beta-blocker therapy should be continued unless contraindicated or poorly tolerated.

3rd line – permanent pacemaker

Back
ACUTE
|
congenital LQTS with previous cardiac event
3rd line – 

permanent pacemaker

Indicated if symptoms continue despite sympathectomy.

If there is a lack of surgical experience in thoracoscopic left cardiac sympathetic denervation (and the patient declines referral to a specialised centre).

Single- or dual-chamber depending on the individual patient and following specialist (cardiologist or electrophysiologist) advice.

Plus – continue beta-blocker, lifestyle modification, and monitoring

Back
ACUTE
|
congenital LQTS with previous cardiac event
Plus – 

continue beta-blocker, lifestyle modification, and monitoring

Treatment recommended for ALL patients in selected patient group

Beta-blocker therapy should be continued unless contra-indicated or poorly tolerated.

When combined with beta-blockers, ventricular pacing, which prevents bradycardia, may facilitate the up-titration of beta-blockers to more effective anti-arrhythmic doses and can also serve to prevent pause-dependent torsades de pointes.[61]

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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