Long QT syndrome (LQTS)


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


    • Class IA and III antiarrhythmics, TCAs, antihistamines.
    • Phenothiazines (Haloperidol)111 ( and quinolone antibiotics).
    • Electrolytes e.g. ↓K+ ↓Mg++, ↓Ca++.
    • Cocaine ± myocardial ischaemia.
    • Acute MI, hypothermia.


    • Romano-Ward syndrome - autosomal dominant.
    • Lange-Nielsen syndrome - autosomal recessive (assoc congenital deafness.
  • F > M, usually childhood or adolescence.
  • Once identified, first 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

Clinical Presentation

  • Palpitations, syncope/near syncope, seizures, cardiac arrest.

ECG findings

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


  • "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 20/02/2009,04/08/12. Last review Dr ÍOS 4/12/18 .