<p>We describe two cases of idiopathic ventricular tachcyardia (VT) arising from the postero-septal right ventricular outflow tract (RVOT) in both cases. Each case demonstrates an important learning point and advantage of multispline multi-electrode mapping catheters in idiopathic outflow VT. In the first case two dominant PVC morphologies can be clearly seen which we believe originate from a single site of origin with multiple exit sites caused by focal fibrosis. In the second case, focal fibrosis in this region leads to anisotropic conduction of the RVOT in areas of low voltage. We surmise that multi-spline multi-electrode catheters are essential in such cases as extensive point-by-point mapping could significantly prolong procedure time and fail to identify the earliest activation site in the case of anisotropic tissue conduction due to variations in activation latency.</p> Graphical abstract <p>Differences between multielectrode mapping and point-by-point mapping demonstrating the impact of electrode spacing on the ability to identify focal fibrosis and adjacent exit sites.</p> <p></p>