Long QT syndrome

Asymptomatic and undiagnosed

These patients may have normal life expectancy and may remain asymptomatic. Patients with congenital LQTS may pass on the specific mutation to their offspring, who may then become symptomatic. Prognosis is variable and depends on risk stratification for the probability of a future cardiac event (syncope, cardiac arrest, or sudden death), which in turn depends on the history of symptoms, genotype, sex, age, and length of the corrected QT interval (QTc).

Asymptomatic and diagnosed

These patients may have normal life expectancy and may remain asymptomatic. Treatment with beta-blockers may be considered if high-risk features are identified. Lifestyle modifications, especially in patients with congenital LQTS, should be emphasised and encouraged. These patients may progress to become symptomatic.[43]Rohatgi RK, Sugrue A, Bos JM, et al. Contemporary outcomes in patients with long QT syndrome. J Am Coll Cardiol. 2017 Jul 25;70(4):453-62. http://www.ncbi.nlm.nih.gov/pubmed/28728690?tool=bestpractice.com

Symptomatic with ≥1 syncopal episodes

These patients are at risk of recurrent syncopal episodes. Careful attention must be given to minimise all identifiable triggers that may prolong the QT interval, including drugs and electrolyte abnormalities. These patients benefit most from treatment with beta-blockers and an implantable cardioverter-defibrillator (ICD).

Symptomatic with cardiac arrest

These patients are at highest risk of recurrent episodes of syncope and/or cardiac arrest. Previous cardiac arrest carries a higher risk of LQTS-related sudden death. Careful attention must be given to minimise all identifiable triggers that may prolong the QT interval, including drugs and electrolyte abnormalities. Survival is enhanced with beta-blocker and ICD therapy.