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Ventricular arrhythmias present with a wide spectrum of clinical manifestations, from mildly symptomatic frequent premature ventricular contractions to life-threatening events. Pathophysiologically, idiopathic ventricular arrhythmias occur in the absence of structural heart disease or ion channelopathies. Ventricular arrhythmias in the context of structural heart disease are usually determined by scar-related reentry and are associated with increased mortality. Catheter ablation is safe and highly effective in treating ventricular arrhythmias. The proper characterization of the arrhythmogenic substrate is essential for accurate procedural planning. We provide an overview on the main mechanisms of ventricular arrhythmias and their implications for catheter ablation.

In patients with nonischemic cardiomyopathy, epicardial ablation is critical in targeting epicardial paravalvular substrate. Epicardial access and ablation can be performed safely with attention to epicardial structures, such as the coronary arteries, phrenic nerve, and epicardial fat. This review explores the indications, techniques, complications, and outcomes of epicardial ablation in patients with nonischemic cardiomyopathy. Although epicardial ablation adds to the complexity and risk of the ablation procedure, it is a vital tool that, combined with endocardial mapping and ablation, improves outcomes in patients with nonischemic cardiomyopathy suffering from ventricular arrhythmias.

Ventricular arrhythmias (VAs) occurring in the absence of structural heart disease or ion channelopathies are referred to as idiopathic. They can clinically present with frequent monomorphic premature ventricular contractions, nonsustained ventricular tachycardia (VT), or sustained VT, and generally share a benign prognosis. Approximately 4% to 10% of idiopathic VAs have an epicardial site of origin, represented in most cases by the left ventricular summit and, less frequently, by the cardiac crux. Epicardial foci can be addressed by catheter ablation via the coronary venous system tributaries. In rarer instances, a direct epicardial access from a subxiphoid approach is needed.

This review discusses the state of the art of knowledge to help decision making in patients who are candidates for cardiac resynchronization therapy (CRT) and to analyze the long-term total and cardiac mortality, sudden death, and CRT with a defibrillator intervention rate, as well as the evolution of echocardiographic parameters in patients with a left ventricular (LV) ejection fraction of greater than 50% after CRT implantation. Owing to normalization of LV function in super-responders, the need for a persistent defibrillator backup is also considered.

Catheter ablation is an increasingly used treatment option for patients with ventricular tachycardia (VT) in the setting of structural heart disease. Although there are extensive data from several retrospective studies as well as prospective nonrandomized observational studies, there are limited data from relatively few randomized controlled trials, especially comparing VT ablation with antiarrhythmic drugs. In this review, the authors aim to summarize the major studies examining efficacy of VT ablation in patients with structural heart disease, discuss barriers to enrollment and completion of randomized clinical trials, and propose areas of future research in the field.