EMed

Long QT syndrome (LQTS)

Background

  • Prolonged ventricular re-polarisation = prolongation of the QT interval
  • Risk of Torsade de pointes and sudden death
  • Congenital or acquired

Acquired

Congenital

  • Romano-Ward syndrome - autosomal dominant
  • Lange-Nielsen syndrome - autosomal recessive (assoc. congenital deafness)
  • F > M, usually childhood or adolescence
  • Once identified, 1st degree relatives should be screened
  Normal QTc Prolonged QTc
Males or females <15 years old <0.44 s >0.46 s
Males > 15 years <0.43 s >0.45 s
Females > 15 years <0.45 s >0.46 s
Long QT syndrome
QT nomogram
QT nomogram (Chan et. al.). HR-QT pairs above the line = ↑ risk of TdP.

Clinical Presentation

  • Palpitations, syncope/near syncope, seizure, cardiac arrest

ECG findings

  • QTc = QT/R-R-2. >0.45 sec abnormal
  • Abnormal T-wave (notched or biphasic)
  • T-wave alternans

Treatment

  • "lifestyle modifications," (avoidance competitive sports and of all drugs known to prolong QT interval) (list)
  • Treat with β-blockers (shorten the QT interval, reduce risk of Torsade and sudden death)
  • High risk patients - implantable cardioverter-defibrillators (ICDs)
  • Left cervicothoracic sympathectomy (block sympathetic to heart so reduce event rate)

Content by Dr Íomhar O' Sullivan. Last review Dr ÍOS 27/09/21 .