Long QT Syndrome risk stratification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]

Overview

The genetic variant (LQT1-8), the gender and the QT interval are associated with the risk of a cardiac event. A history of prior events (syncope, fainting spells, seizures, sudden death) and a family history of cardiac events are associated with an increased risk of subsequent cardiac events.

Risk Factors for Torsade de Pointes and Sudden Cardiac Death

Persons with a history of repeated fainting episodes or syncope. If there are more than 2 fainting spells in under 2 years, the risk of an aborted SCD or SCD is increased 18 fold.^[1]
Repeated blackouts or fainting spells in the context of the following are due to a malignant arrhythmia until proven otherwise:

Exertion
Loud startling noise
Postpartum syncope
Seizures

A prior history of cardiac arrest.
Family members of persons with repeated fainting, accidents, seizures or a history of cardiac arrest.
Persons who are on certain medications that are known to cause a prolonged QT interval on electrocardiogram.
Persons who are first degree relatives of people with know long QT syndrome.
Persons who suffer from anorexia nervosa, or who have low levels of magnesium, calcium or potassium in their blood

Risk stratification

The risk for an untreated LQTS patients sustaining an events (syncope or cardiac arrest) can be predicted from their genotype (LQT1-8), gender and corrected QT interval.^[2]

High risk

Risk of event: >50%

QTc > 500 msec LQT1 & LQT2 & LQT3(males)

Intermediate risk

Risk of event: 30-50%

QTc > 500 msec LQT3(females)

QTc < 500 msec LQT2(females)& LQT3

Low risk

Risk of event: <30%

QTc < 500 msec LQT1 & LQT2 (males)

Risk of Arrhythmias and Medications to be Avoided in Congenital Long QT Syndrome

References

↑ Hobbs et al. JAMA 296:1249-1254, 2006.
↑ Risk Stratification in the Long-QT Syndrome: N Engl J Med 2003; 349:908-909, Aug 28, 2003. PMID 12944579.

[1] Hobbs et al. JAMA 296:1249-1254, 2006.

[2] Risk Stratification in the Long-QT Syndrome: N Engl J Med 2003; 349:908-909, Aug 28, 2003. PMID 12944579.

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