The STAR VT trial is a randomized trial examining the

The STAR-VT trial is a randomized trial examining the role of ablation in patient with an indication for ICD implantation [97]. The inclusion criteria targeting 562 patients with secondary prevention indications as well as primary prevention patients with inducible VT, where nonischemic cardiomyopathy patients will be included and epicardial ablation is encouraged.
Conclusions
Conflict of interest
Introduction Catheter ablation is an effective treatment that can cure ventricular tachycardias (VTs). VTs secondary to structural heart diseases are usually first treated by antiarrhythmic drugs and implantable cardioverter-defibrillators. When patients cannot tolerate antiarrhythmic drugs or antiarrhythmic drugs cannot control VTs, resulting in multiple shocks from the defibrillator, catheter ablation of the VTs should be considered [1]. On the other hand, catheter ablation may currently be a first line treatment for idiopathic VTs because of its high success rate and low risk of complications [2]. VTs can usually be treated by endocardial catheter ablation. However, some VTs can arise from the epicardial surface, and their substrate can be altered only by epicardial catheter ablation [2,3]. There are two approaches in epicardial catheter ablation: transvenous and transthoracic [2,3]. The transvenous approach through the coronary venous system (CVS) has been commonly used because it is easily accessible. However, this approach may be limited by the distribution of the CVS and insufficient radiofrequency UO126 delivery. Pioneering work on transthoracic epicardial catheter ablation to treat VT via a transpericardial approach was first reported by Sosa and his colleagues in 1996 [4]. Since then, epicardial substrates of VTs have been increasingly recognized and transthoracic epicardial mapping and catheter ablation have been proven to enhance the success rate of catheter ablation of VTs and to help the patients avoid a surgical procedure [4–6]. This review discusses how to recognize, map and ablate epicardial VTs and how to prevent, recognize, and manage the complications associated with epicardial VT ablation.
How to recognize epicardial VT?
How to map epicardial VT?
How to ablate epicardial VT? An irrigated radiofrequency ablation catheter is used for epicardial sites accessed via the transvenous or transthoracic pericardial approaches. Irrigation enables radiofrequency energy to be delivered to locations where little or no convective cooling of the ablation electrode by blood flow occurs. Irrigated radiofrequency ablation is more effective than non-irrigated radiofrequency energy for generating epicardial lesions in the presence of epicardial fat interposed between the ablation electrode and the target site in the myocardium [18]. The ablation electrode can be irrigated either internally or externally. Irrigated radiofrequency ablation is delivered for 1–2min at each ablation site with the electrode in power-control mode, starting at 20W in the CVS, including the great cardiac vein, anterior interventricular vein and middle cardiac vein, and 30W on the epicardial surface, with an irrigation flow rate of 30mL/min [19,20]. If the initial radiofrequency power is not effective, it is increased to a maximum of 30W in the CVS, and 50W on the epicardial surface; care is taken to limit the electrode temperature to <41°C [20]. During this treatment, a decrease in the impedance of 5–10Ω represents the formation of good radiofrequency lesions. The efficacy of transvenous and transthoracic epicardial radiofrequency ablation might be limited by its inaccessibility to the myocardial site of origin, close proximity to the coronary artery, or an epicardial location that lies beneath a fat pad (i.e., near the atrioventricular groove). Cryothermal ablation might be a viable alternative to radiofrequency ablation in patients with a high impedance over a thick fat pad, or a VT origin close to a coronary artery, because it is not limited by impedance and is safer than radiofrequency ablation, posing a lower risk of damage to the vessel and thrombus formation [13]. An absence of circulating blood in the pericardial space may favor the creation of cryo-lesions on the epicardium.