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Updated: Apr 29, 2026
Electrocardiogram Recordings in Anesthetized Mice using Lead II
Published on: June 20, 2020
Early repolarization is associated with symptoms in patients with type 1 and type 2 long QT syndrome
Zachary W M Laksman1, Lorne J Gula1, Pradyot Saklani1
1Division of Cardiology, University of Western Ontario, London, Ontario, Canada.
Background:
Early repolarization (ER) is associated with an increased risk for death from cardiac causes. Recent evidence supports ER's role as a modifier and/or predictor of risk in many cardiac conditions.
Objective:
The purpose of this study was to determine the prevalence of ER among genotype-positive patients with long QT syndrome (LQTS) and evaluate its utility in predicting the risk of symptoms.
Methods:
ER was defined as QRS slurring and/or notching associated with ≥1-mV QRS-ST junction (J-point) elevation in at least 2 contiguous leads, excluding the anterior precordial leads. The ECG with the most prominent ER was used for analysis. Major ER was defined as ≥ 2-mm J-point elevation. Symptoms of LQTS included cardiac syncope, documented polymorphic ventricular tachycardia (VT), and resuscitated cardiac arrest.
Results:
One hundred thirteen patients (mean age 41 ± 19 years; 63 female) were reviewed, among whom 414 (mean 3.7 ± 1.5) ECGs were analyzed. Of these, 30 patients (27%) with a history of symptoms. Fifty patients (44%) had ER, and 19 patients (17%) had major ER. Patients with major ER were not different from patients without major ER with respect to age, sex, long QT type, longest QTc recorded, number of patients with QTc >500 ms, or use of beta-blockade. Univariate and independent predictors of symptom status included the presence of major ER, longest QTc recorded >500 ms, and female sex.
Conclusion:
ER ≥2 mm was the strongest independent predictor of symptom status related to LQTS, along with female sex and QTc >500 ms.
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