6th March 2024

Congenital Long QT Syndrome (LQTS)

These consist of numerous, mainly autosomal dominant, genetic defects encoding for ion channel proteins, which prolong ventricular repolarisation, resulting in prolongation of the QT interval (QTc >440ms in men and >460ms in women). This is achieved by reduced outflow of potassium or prolonged inflow of sodium. Prolonging of the QT interval may result in a polymorphic VT with the typical characteristic of Torsades de Pointes. This may be triggered by increased sympathetic activity such as exercise or emotional stress. There are three main genetic subtypes shown in Table 4:

Table 4: Genetic subtypes of LQTS

The long QT may be identified after the patient presents with symptoms of palpitations or syncope. The Schwartz score helps to offer the likelihood that a patient has LQTS. Beta-blockade is used in these patients and ICD is implanted in high-risk patients. It is worth mentioning that there are eponymous syndromes including ‘Jervell and Lange-Nielsen’ and ‘Romano-Ward’ with which patients have LQTS but with associated hearing loss or no-hearing loss respectively.