T-Wave morphology in short QT syndrome.
BACKGROUND
Short QT syndrome (SQTS) is an inherited disorder characterized by a short QT interval and vulnerability to ventricular tachyarrhythmias. The diagnostic criteria for this syndrome are not well defined, since there is uncertainty about the lowest normal limits for the corrected QT (QTc) interval.


OBJECTIVE
The aim of this study was to determine whether T-wave morphology parameters are abnormal in short QT subjects and whether those parameters can help in the diagnosis of SQTS.


RESULTS
We describe three families (10 patients) with short QT intervals (QTc 310 +/- 32 ms). Seven subjects had suffered serious arrhythmic events and three were asymptomatic. T-wave morphology was assessed using the principal component analysis (PCA). QTc was significantly shorter and T-wave amplitude in lead V2 higher in the short QT subjects compared to healthy controls (n=149), (P < 0.001 for both). The total cosine of the angle between the main vectors of the QRS and T-wave loops (TCRT) was markedly abnormal among the symptomatic patients with short QT syndrome (n=7) (TCRT -0.14 +/- 0.55 vs 0.36 +/- 0.51, P=0.019). None of the three asymptomatic patients with short QT but without a history of arrhythmic events had an abnormally low TCRT.


CONCLUSIONS
Our observations suggest that patients with a short QT interval and a history of arrhythmic events have abnormal T-wave loop parameters. These electrocardiogram (ECG) features may help in the diagnosis of SQTS in addition to the measurement of the duration of QT interval from the 12-lead ECG.
Anttonen
Olli
O
Päijät-Häme Central Hospital, Lahti, Finland.
Junttila
Juhani
J
Giustetto
Carla
C
Gaita
Fiorenzo
F
Linna
Eeva
E
Karsikas
Mari
M
Seppänen
Tapio
T
Perkiömäki
Juha S
JS
Mäkikallio
Timo H
TH
Brugada
Ramon
R
Huikuri
Heikki V
HV
D000328:Adult; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology*; D002648:Child; D004562:Electrocardiography; D005260:Female; D005387:Finland; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D013577:Syndrome