Ventricular arrhythmias are responsible for the majority of sudden cardiac deaths (SCD), particularly in patients with structural heart disease. Coronary artery disease, essentially previous myocardial infarction, is the most common heart disease upon which sustained ventricular tachycardia (VT) occurs, being reentry the predominant mechanism. Other cardiac conditions, such as idiopathic dilated cardiomyopathy, Chagas disease, sarcoidosis, arrhythmogenic cardiomyopathies, and repaired congenital heart disease may also present with VT in follow-up. Analysis of the 12-lead electrocardiogram (ECG) is essential for diagnosis. There are numerous electrocardiographic criteria that suggest VT with good specificity. The ECG also guides us in locating the site of origin of the arrhythmia and the presence of underlying heart disease. The electrophysiological study provides valuable information to establish the mechanism of the arrhythmia and guide the ablation procedure, as well as to confirm the diagnosis when dubious ECG. Given the poor efficacy of antiarrhythmic drug therapy, adjunctive catheter ablation contributes to reduce the frequency of VT episodes and the number of shocks in patients implanted with a cardioverter-defibrillator (ICD). ICD therapy has proven to be effective in patients with aborted SCD or sustained VT in the presence of structural heart disease. It is the only therapy that improves survival in this patient population and its implantation is unquestioned nowadays
