Long QT syndrome in adults.
OBJECTIVE
The aims of this study were: 1) to evaluate risk factors influencing the clinical course of mutation-confirmed adult patients with long QT syndrome (LQTS), 2) to study life-threatening cardiac events as a specific end point in adults, and 3) to examine the protective effect of beta-blocker therapy on cardiac events in adult LQTS patients with known cardiac channel mutations.


BACKGROUND
The clinical course and risk factors for cardiac events in genotype-confirmed adult patients with LQTS have not been previously investigated.


METHODS
The clinical characteristics of 812 mutation-confirmed LQTS patients age 18 years or older were studied with both univariate and multivariate analyses to determine the genotype-phenotype factors that influence the clinical course of adult patients with this disorder.


RESULTS
Female gender, corrected QT (QTc) interval, LQT2 genotype, and frequency of cardiac events before age 18 years were associated with increased risk of having any cardiac events between the ages of 18 and 40 years. Female gender, QTc interval > or =500 ms, and interim syncopal events during follow-up after age 18 years were associated with significantly increased risk of life-threatening cardiac events in adulthood. Beta-blockers provided a 60% reduction in risk of any cardiac event and life-threatening events, with somewhat greater effect in higher-risk subjects.


CONCLUSIONS
The severity of LQTS in adulthood can be risk stratified with information regarding genotype, gender, QTc duration, and history of cardiac events. Beta-blockers effectively reduce but do not eliminate the risk of both syncopal and life-threatening cardiac events in adult patients with mutation-confirmed LQTS.
Sauer
Andrew J
AJ
Cardiology Unit of the Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642-8653, USA.
Moss
Arthur J
AJ
McNitt
Scott
S
Peterson
Derick R
DR
Zareba
Wojciech
W
Robinson
Jennifer L
JL
Qi
Ming
M
Goldenberg
Ilan
I
Hobbs
Jenny B
JB
Ackerman
Michael J
MJ
Benhorin
Jesaia
J
Hall
W Jackson
WJ
Kaufman
Elizabeth S
ES
Locati
Emanuela H
EH
Napolitano
Carlo
C
Priori
Silvia G
SG
Schwartz
Peter J
PJ
Towbin
Jeffrey A
JA
Vincent
G Michael
GM
Zhang
Li
L
D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D017677:Age Distribution; D015331:Cohort Studies; D016757:Death, Sudden, Cardiac / Q000453:epidemiology*; D004562:Electrocardiography; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D051657:KCNQ1 Potassium Channel / Q000235:genetics*; D008133:Long QT Syndrome / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality*; D008297:Male; D009154:Mutation; D016016:Proportional Hazards Models; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D018709:Statistics, Nonparametric; D016019:Survival Analysis
D000319:Adrenergic beta-Antagonists; D051657:KCNQ1 Potassium Channel