Objective:The objective was to provide a brief history of J wave syndromes and to summarize our current understanding of their molecular,ionic,cellular mechanisms,and clinical features.We will also discuss the existing debates and further direction in basic and clinical research for J wave syndromes.Data Sources:The publications on key words ofJ wave syndromes,early repolarization syndrome (ERS),Brugada syndrome (BrS) and ST-segment elevation myocardial infarction (STEMI) were comprehensively reviewed through search of the PubMed literatures without restriction on the publication date.Study Selection:Original articles,reviews and other literatures concing J wave syndromes,ERS,BrS and STEMI were selected.Results:J wave syndromes were firstly defined by Yan et al.in a Chinese joal a decade ago,which represent a spectrum of variable phenotypes characterized by appearance of prominent electrocardiographic J wave including ERS,BrS and ventricular fibrillation (VF) associated with hypothermia and acute STEMI.J wave syndromes can be inherited or acquired and are mechanistically linked to amplification of the transient outward current (Ito)-mediated J waves that can lead to phase 2 reentry capable of initiating VF.Conclusions:J wave syndromes are a group of newly highlighted clinical entities that share similar molecular,ionic and cellular mechanism and marked by amplified J wave on the electrocardiogram and a risk of VF.The clinical challenge ahead is to identify the patients with J wave syndromes who are at risk for sudden cardiac death and determine the altative therapeutic strategies to reduce mortality.