High prevalence of early repolarization in short QT syndrome.
BACKGROUND
Short QT syndrome (SQTS) is characterized by an abnormally short QT interval and sudden death. Due to the limited number of cases, the characteristics of SQTS are not well understood. It has been reported recently that early repolarization is associated with idiopathic ventricular fibrillation and the QT interval is short in patients with early repolarization.


OBJECTIVE
The purpose of this study was to study the association between early repolarization and arrhythmic events in SQTS.


METHODS
The study consisted of three cohorts: SQTS cohort (N = 37), control cohort with short QT interval and no arrhythmic events (N = 44), and control cohort with normal QT interval (N = 185). ECG parameters were compared among the study cohorts.


RESULTS
Heart rate, PR interval, and QRS duration were similar among the three study cohorts. Early repolarization was more common in the SQTS cohort (65%) than in the short QT control cohort (30%) and the normal QT control cohort (10%). Duration from T-wave peak to T-wave end was longer in the SQTS cohort than in the short QT control cohort, although QT and corrected QT intervals were similar. In the SQTS cohort, there were more males among patients with arrhythmic events than in those with a family history but without arrhythmic events. In multivariate models, early repolarization was associated with arrhythmic events in the SQTS cohort. ECG parameters including QT and QTc intervals were not associated with arrhythmic events in the SQTS cohort.


CONCLUSIONS
There is a high prevalence of early repolarization in patients with SQTS. Early repolarization may be useful in identifying risk of cardiac events in SQTS.
Watanabe
Hiroshi
H
Division of Cardiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
Makiyama
Takeru
T
Koyama
Taku
T
Kannankeril
Prince J
PJ
Seto
Shinji
S
Okamura
Kazuki
K
Oda
Hirotaka
H
Itoh
Hideki
H
Okada
Masahiko
M
Tanabe
Naohito
N
Yagihara
Nobue
N
Kamakura
Shiro
S
Horie
Minoru
M
Aizawa
Yoshifusa
Y
Shimizu
Wataru
W
D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D016022:Case-Control Studies; D015331:Cohort Studies; D016001:Confidence Intervals; D000072237:ERG1 Potassium Channel; D004562:Electrocardiography; D051638:Ether-A-Go-Go Potassium Channels / Q000235:genetics; D005260:Female; D005819:Genetic Markers; D005820:Genetic Testing; D006339:Heart Rate; D006801:Humans; D007564:Japan / Q000453:epidemiology; D051657:KCNQ1 Potassium Channel / Q000235:genetics; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics; D015995:Prevalence; D012307:Risk Factors; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D055815:Young Adult
D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D005819:Genetic Markers; C489457:KCNJ2 protein, human; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; D024661:Potassium Channels, Inwardly Rectifying