ECG patterns related to arrhythmias and sudden death: channelopathies, early repolarization, and pre-excitation

Abstract Electrocardiogram (ECG) patterns recognized in patients with sudden death without structural abnormalities in the heart have guided cardiology over the last few decades towards a better understanding of the role of cardiac ion channels in physiology and in arrhythmogenicity in rare electrical diseases. The long QT syndrome became the paradigm for evaluating the association between specific ion channel abnormalities caused by mutations in genes encoding predominantly potassium and sodium channels and phenotypic ECG expression. Specific ECG patterns observed in long QT syndrome help in diagnosis and improve prognosis in patients affected by this disorder. Short QT syndrome also is characterized by specific patterns in repolarization morphology that relate to affected potassium current or calcium handling genes. Brugada syndrome and early repolarization syndrome are considered as J-wave syndromes, having some similarities in ECG features but with distinctive patterns associated with classical forms of these disorders. Spontaneous appearance of cove-type Brugada pattern is associated with a worse prognosis. Early repolarization patterns may also indicate prognosis in subjects with a prior history of cardiac arrest or ventricular arrhythmias or a family history of cardiac arrests. Catecholaminergic polymorphic ventricular tachycardia is another channelopathy without characteristic features in standard resting ECG but with characteristic polymorphic ventricular arrhythmias during catecholaminergic challenge (exercise test, stressing situations). Pre-excitation syndromes associated with sudden cardiac death are well recognized and current understanding of these disorders leads to a better therapy.