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Synonyms: autosomal-dominant long QT syndrome, long QT syndrome type 1, LQTS1, RWS, Romano-Ward long QT syndrome, Ward-Romano syndrome
Romano-Ward syndrome is an inherited heart disorder characterised by prolongation of the QT interval, often in association with episodes of ventricular tachyarrhythmia, torsades de pointes, syncope and sudden death.[1]
KCNQ1 (formerly called KVLQT1) is a voltage-gated potassium-channel gene responsible for the long QT 1 subtype of long QT syndromes. In general, heterozygous mutations in KCNQ1 cause Romano-Ward syndrome (LQT1 only), while homozygous mutations cause Jervell and Lange-Nielsen syndrome (LQT1 and deafness).[2]
Attacks of ventricular tachyarrhythmia are usually associated with sympathetic stimulation such as exercise, stress or emotion, dependent on genotype.
Epidemiology
- The disorder may be sporadic or transmitted as an autosomal-dominant trait.
- Six different genes have so far been identified as being involved in the development of congenital long QT syndromes[3] and heterozygote mutations in KCNQ1 (a potassium-channel gene) are thought to be responsible for Romano-Ward syndrome.[2]
Presentation
- The severity ranges from those with no apparent symptoms to others who develop tachyarrhythmias resulting in episodes of syncope, cardiac arrest and, potentially, sudden death.
- Between such episodes, sinus bradycardia is often seen.
- There may be a family history of recurrent syncope or sudden death.
Differential diagnosis
Other causes of prolongation of the QT interval:
- Congenital: Jervell and Lange-Nielsen syndrome, which is associated with deaf mutism and transmitted as autosomal recessive.
- Acquired:
- Electrolyte disturbances: hypokalaemia, hypocalcaemia, hypomagnesaemia.
- Hypothermia.
- Drugs:
- Anti-arrhythmic drugs: amiodarone, sotalol, disopyramide.
- Tricyclic antidepressants.
- Non-sedative antihistamines: terfenadine, astemizole (both now withdrawn).
- Antibiotic (erythromycin), and antimalarial (halofantrine).
Investigations
- The diagnosis should be considered in all patients who present with syncope.
- An ECG with calculation of the QT interval should be performed on all patients with a suggestive history.
- All other family members must be fully assessed.
Management
- Drug treatment:[4]
- Betablockers are the drugs of choice.
- Betablockers are effective in preventing cardiac events in approximately 70% of patients.
- Propranolol and nadolol are the betablockers most frequently used, but atenolol and metoprolol are also used.
- If drug treatment is unsuccessful then selective high left stellate ganglionectomy has been shown to be effective.[5]
- Permanent pacing in combination with betablockers may also be effective in reducing symptoms.
- For high-risk patients, an implantable cardioverter defibrillator (ICD) reduces mortality.[6]
- Defibrillator implantation is often a first-line therapy if there has been a cardiac arrest.
Prognosis
The prognosis of untreated congenital long QT syndrome is poor, with a high incidence of sudden death in childhood.
Further reading and references
Watanabe A, Nakamura K, Morita H, et al; Long QT syndrome. Nippon Rinsho. 2005 Jul63(7):1171-7.
Herbert E, Trusz-Gluza M, Moric E, et al; KCNQ1 gene mutations and the respective genotype-phenotype correlations in the long QT syndrome. Med Sci Monit. 2002 Oct8(10):RA240-8.
Haack B, Kupka S, Ebauer M, et al; Analysis of candidate genes for genotypic diagnosis in the long QT syndrome. J Appl Genet. 200445(3):375-81.
Sovari AA et al; Long QT Syndrome, Medscape, Jun 2012
Moss AJ, McDonald J; Unilateral cervicothoracic sympathetic ganglionectomy for the treatment of long QT interval syndrome. N Engl J Med. 1971 Oct 14285(16):903-4.
Chiang CE; Congenital and acquired long QT syndrome. Current concepts and management. Cardiol Rev. 2004 Jul-Aug12(4):222-34.