Clinical Significance

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Clinical Significance

The early repolarisation pattern has long been considered to be a benign ECG manifestation (6–13 % in the general population), that is seen more commonly in young healthy men and athletes (22–44 %) and its clinical significance has been questioned.⁷ In a recent report on professional athletes, a correlation between J-point elevation and interventricular septum thickness was observed, suggesting a possible mechanistic role of exercise-induced left ventricular hypertrophy as the basis for J-point elevation, and no cardiac death was observed in a median of 13 years follow-up.⁸ Similarly, in the CARDIA study, the presence of early repolarisation in young adults was not associated with higher risk of death during long-term follow-up.⁹ The possibility that false tendons, e.g. discrete, fibromuscular structures that transverse the LV cavity, are related to the genesis of J waves has also been raised.¹⁰

However, there has been evidence suggesting that the early repolarisation pattern may be associated with a risk for VF, depending on the location of early repolarisation, magnitude of the J wave and degree of ST elevation.^2,11,12 In a large study on a community- based general population of 10,864 middle-aged subjects, an early repolarisation pattern with J-point elevation of at least 0.1 mV in the inferior leads of a resting ECG was associated with an increased risk of death from cardiac causes.¹³ In addition, among patients with a history of idiopathic ventricular fibrillation, an increased prevalence of early repolarisation, (up to 23 %), defined as an elevation of the QRS– ST junction of at least 0.1 mV from baseline in the inferior or lateral lead, manifested as QRS slurring or notching, has been detected.^11,14 A higher prevalence of J-wave and/or QRS slurring (but not of ST elevation) has been found among athletes with cardiac arrest/sudden death than in controls.¹⁵ A horizontal/descending type (defined as ≤0.1 mV elevation of the ST segment within 100 ms after the J point) in the inferior leads, as opposed to a rapidly ascending ST segment type, may help to identify those individuals who are clearly at risk (see Figure 2).^16,17 Coexistence of an anterior early repolarisation pattern (e.g. in leads V1–V3),¹⁸ and early repolarisation in the inferior leads, especially in cases without other QRS complex abnormalities, predict the occurrence of VT/VF.¹⁹

Still, several obscure points remain with this syndrome. An early repolarisation pattern in the inferolateral leads occurs in 5 % of apparently healthy individuals;^13,14 it may not be consistently seen, and even the horizontal/descending ST type was seen in 3 % of controls.^16,17 In the Atherosclerosis Risk in Communities (ARIC) study, J-point elevation was associated with an increased risk of sudden cardiac death (SCD) in whites and in women, but not in blacks or men.²⁰ A pattern of J-wave and/or QRS slurring (but not of ST elevation) has been associated with cardiac arrest/sudden death in athletes,¹⁵ but many healthy athletes have early repolarisation with a rapidly ascending pattern. Inferolateral early repolarisation pattern is seen in 25–35 % of competitive athletes, and inferior only in 4 %, and is considered a dynamic phenomenon related to physical activity.^8,21,22 Finally, a large genome-wide association study has been unable to identify genetic variants associated with the pattern, possibly reflecting the phenotypic heterogeneity that exists among these individuals.²³ It seems, therefore, that the majority of individuals with early repolarisation are at no or minimal risk for arrhythmic events.²