Inferolateral early repolarization among non-ischaemic sudden cardiac death victims

Abstract

Aim: Inferolateral early repolarization (ER) has been associated with an increased risk of sudden cardiac death (SCD). However, this association is thought to be mainly due to ischaemic SCD. The association of ER and non-ischaemic SCD has not been studied. The aim was to evaluate whether inferolateral ER is associated with non-ischaemic SCD.

Methods and results: Study population consists of 275 consecutive victims of non-ischaemic SCD with 12-lead ECG and control group of general population cohort with 10 864 subjects. Sudden cardiac deaths were verified as non-ischaemic by medicolegal autopsy. Hypertensive cardiomyopathy (HTCMP) (25%), alcohol related dilated cardiomyopathy (ACMP) (24%), obesity associated cardiomyopathy (OCMP) (23%), and idiopathic myocardial fibrosis (IMF) (15%) were the most common causes of non-ischaemic SCD. A structurally normal heart was seen in only 1.5%. The prevalence of inferolateral ER was 20.7% among patients with non-ischaemic SCD compared to 5.3% in the general population (P < 0.001). The ECG pattern was accompanied with a horizontal/descending ST segment in 95% of the cases. The prevalence of inferolateral ER was slightly higher in the HTCMP group (26%) and the ACMP group (24%) than in the IMF group (20%) and the OCMP group (13%). The history of previously diagnosed cardiac diseases was not higher among subjects with ER (55%) than those without (59%, P = 0.59).

Conclusion: The prevalence of inferolateral ER among non-ischaemic SCD victims is high. Almost all ER patterns are accompanied with the malignant horizontal/descending ST segment morphology suggesting that inferolateral ER is not only associated with an ischaemic SCD but also a non-ischaemic SCD.