12-lead electrocardiogram features of arrhythmic risk: A focus on early repolarization

Table 1 The main studies evaluating the relationship between early repolarization pattern and death due to arrhythmia

Ref.	No. of patients	Study population	ER pattern	Results
Tikkanen et al[36], 2009	10.864	Community-based general population of middle-aged subjects	ER was stratified according to the degree of J-point elevation (> or = 0.1 mV or > 0.2 mV) in either inferior or lateral leads	ER pattern in the inferior leads is associated with an increased risk of death from cardiac causes in middle-aged subjects
Tikkanen et al[35], 2011	565 young healthy athletes-10 864 middle- aged subjects	565 young healthy athletes compared with ECGs from a general population of 10864 middle-aged subjects	ER pattern with horizontal/descending or rapidly ascending/upsloping	ST-segment morphology variants associated with ER separates subjects with and without an increased risk of arrhythmic death in middle-aged subjects. Rapidly ascending ST segments after the J- point, the dominant ST pattern in healthy athletes, seems to be a benign variant of ER
Uberoi et al[43], 2011	29281	Resting ambulatory ECGs	J-point elevation ≥ 0.1 mV- notching and slurring type in at least 2 lateral or inferior-lateral leads	No significant association between any components of early repolarization and cardiac mortality
Haïssaguerre et al[10], 2008	206	Patients who were resuscitated after cardiac arrest due to IVF	Elevation of the QRS-ST junction of at least 0.1 mm inferior or lateral lead- QRS slurring or notching	Correlation between ER and sudden cardiac arrest
Nam et al[41], 2008	1410	1595 controls and 15 patients with IVF	J-point elevation ≥ 0.1 mV- notching and slurring type in at least 2 lateral or inferior leads	ER pattern is indicative of a highly arrhythmogenic substrate
Rosso et al[42], 2008	290	45 patients with idiopathic VF were compared with 124 age- and gender- matched control subjects and with 121 young athletes	J-point elevation ≥ 0.1 mV- notching and slurring type in at least 2 lateral or inferior-lateral leads	J-point elevation is found more frequently among patients with idiopathic VF than among healthy control subjects. The frequency of J-point elevation among young athletes is intermediate
Rosso et al[29], 2011	8980	331 patients with IVF and 8.649 controls	J waves > 2 mm	The presence of J waves > 2 mm in amplitude in asymptomatic adults is associated with a threefold increased of arrhythmic death
Aizawa et al[45], 2012	116	Forty patients with J-wave-associated idiopathic VF compared with 76 non-VF patients	J-wave amplitude was measured in the beat immediately after a pause and compared with the mean J-wave measured in almost three beats before the pause. J waves were defined as those ≥ 0.1 mV above the isoelectric line	Pause-dependent augmentation of J waves was confirmed in about one-half of the patients with idiopathic VF after sudden R-R prolongation. Such dynamicity of J waves was specific to idiopathic VF and may be used for risk stratification
Cappato et al[37], 2010	386	21 athletes with a history of previous cardiac arrest of unknown etiology compared with more than 300 healthy athletes	ER pattern with horizontal/descending or rapidly ascending/upsloping	Athletes with a horizontal pattern of ER and ST were 11 times more at risk of cardiac arrest
Naruse et al[38], 2012	220	patients with AMI	elevation of the QRS-ST junction of > 0.1 mV - 2 inferior or lateral leads- QRS slurring or notching	The presence of ER increased the risk of VF occurrences within 48 hours after the AMI onset
Rudic et al[40], 2012	60	Patients with AMI	J-point elevation ≥ 0.1 mV- notching and slurring type- in at least 2 lateral or inferior leads	Early repolarization pattern seems to be associated with ventricular tachyarrhythmias in the setting of acute myocardial infarction
Tikkanen et al[39], 2012	964	432 consecutive victims of SCD because of acute coronary event and 532 survivors of such an event	elevation of the QRS-ST junction of > 0.1 mV - 2 inferior or lateral leads- QRS slurring or notching	The presence of ER increases the vulnerability to fatal arrhythmia during acute myocardial ischemia
Wu et al[44], 2013		meta-analysis		Correlation of ER with a higher risk of arrhythmic death but not of cardiac death or death from other causes

ER: Early repolarization; IVF: Idiopathic ventricular fibrillation; AMI: Acute myocardial infarction; SCD: Sudden cardiac death.