LVS definition and anatomy
The LVS is a triangular area located at the most superior portion of the left epicardial ventricular region, surrounded by the two branches of the left coronary artery: the left anterior interventricular artery and the left circumflex artery [9]. The triangle is bounded by septal and mitral margins (Figure 1). A delineation by an arched line, with the radius of this arc being the distance from the left coronary bifurcation artery to the first prominent left coronary artery septal perforator, represents the most inferior boundary of this arc region (triangle base). Inside this triangular area, the anterior interventricular cardiac vein (that travels through the anterior part of the atrioventricular groove) becomes the great cardiac vein that is further heading to the posterior part of the atrioventricular groove [10–14]. Thus, the great cardiac vein/anterior interventricular cardiac vein bisects the LVS into two distinct areas: superior area (also named the inaccessible area for radiofrequency ablation because of the significant risk of coronary vasculature damage) and inferior area (the accessible area for radiofrequency ablation, where the interventions are relatively safe) (Figure 1A) [7]. Each part of the LVS has a specific relation to the adjacent anatomical structures, and each will be described below (Figure 1).