CONGENITAL LQTS – AN ELECTROCARDIOGRAPHIC AND GENOTYPE CORRELATION
AbstractThe congenital Long QT Syndrome (LQTS) is characterized by abnormally prolonged ventricularrepolarization due to inherited defect in cardiac sodium and potassium channels, whichpredisposes the patients to syncope, ventricular arrhythmias, and sudden cardiac death. Earlydiagnosis and preventive treatment are instrumental to prevent sudden cardiac death in patientswith the congenital LQTS. The diagnostic criteria for congenital LQTS are based on certainelectrocardiographic findings and clinical history. Recently genotype specific electrocardiographicpattern in the congenital LQTS has also been described. Recent studies suggest feasibility ofgenotype specific treatment of LQTS and, in near future, mutation specific treatment will probablybecome a novel approach to this potentially fatal syndrome. We describe two cases that fulfilledthe electrocardiographic and historical diagnostic criteria with morphology on electrocardiogram(ECG) suggestive of LQT1 genotype.Keywords: Congenital LQTS, ECG, genotype, pregnancy
Chiang CE, Roden DM. The long QT syndromes: genetic basis
and clinical implications. J Am Coll Cardiol 2000; 36:1-12.
Scwartz PJ. The long QT syndrome. Circulation 1993;88:782-
Zhang G, Timothy KW, Vincent GM. Spectrum of ST-T-wave
patterns and repolarization parameters in congenital long-QT
syndrome: ECG findings identify genotypes. Circulation 2000;
Moss AJ, Zareba W, Benhorin J. ECG T-wave patterns in
genetically distinct forms of the hereditary long QT syndrome.
Moss AJ, Zareba W, Kaufman ES. Increased risk of
arrhythmic events in long QT syndrome with mutations in the
pore region of the human ether-a-a-go-go-related gene
potassium channel. Circulation 2002; 105:794-9.
Priori SG, Napolitano C, Schwartz PJ. Low penetrance in the
long QT syndrome: clinical impact. Circulation 1999; 99:529-
Viskin S. Long QT syndromes and torsades de pointes. Lancet
Donger C, Denjoy I, Berthet M. KVLQT1 C-terminal
missense mutation causes a forme fruste long-QT syndrome.
Dofetilide product monograph and confirmation of education.
New York, NY: Pfizer Inc; March 2000.
Rashba EJ, Zareba W, Moss AJ, Hall WJ, Robinson J, Locati
EH, et al. Influence of pregnancy on the risk of cardiac events
in patients with hereditary long QTsyndrome. LQTS
investigators. Circulation 1998; 97:451-6.
Zareba W, Moss AJ, Schwartz PJ, Vincent GM, Robinson JL,
Priori SG, et al. Influence of genotype on the clinical course of
the long QT-syndrome. International Long QT Syndrome
Regisrty Research Group. N Engl J Med 1998;339:960-5.
Schwartz PJ, Priori SG, Spazzolini C, Moss AJ, Vincent GM,
Napolitano C, et al. Genotype-phenotype correlation in the
long-QT syndrome: gene-specific triggers for life-threatening
arrhythmias. Circulation 2001;103:89-95.
Moss AJ, Zareba W, Hall WJ, Schwartz PJ, Crampton RS,
Benhorin J, et al. Effectiveness and limitations of beta-blocker
therapy in congenital long-QT syndrome. Circulation
Scwartz PJ, Priori SG, Locati EH, Napolitano C, Cantu F,
Towbin JA, et al. Long QT syndrome patients with mutations
of the SCN5A and HERG genes have differential responses to
Na channel blockade and to increases in heart rate.
Implications for gene-specific therapy. Circulation 1995;