www.ipej.org 286 Editorial Mapping for the Target Sites of Ablation in Post-infarction Ventricular Tachycardia- Is Sinus Rhythm Sufficient?

All truths are easy to understand once they are discovered; the point is to discover them- Galileo Galilei (1564 – 1642) The long road to success with radiofrequency ablation for scar-related ventricular tachycardia (VT) has taken the electrophysiologists down many unexpected paths in the last two decades. During this period, the progress in defining the pathological circuits involved in genesis of this complex tachyarrhythmia has undoubtedly improved the ablation outcome. However, empiricism still prevails as to how optimally map the ablation targets of this arrhythmia commonly encountered in clinical practice. It is now clear that scar-related VT is caused by macroreentrant circuits within or adjacent to the scar that forms after myocardial infarction [1,2]. Small strands of surviving myocardium or Purkinje fibres form anisotropic and slow conduction in these areas and serve as ideal substrates for re-entrant circuits. The success of VT ablation, hence, depends on identifying and ablating the critical parts of these re-entrant circuits [2,3]. In hemodynamically stable VTs, these sites can be identified by recognition of late diastolic potentials (LDP) and response to entrainment pacing at sites with LDPs [4] (Figure 1). However, many factors make this approach difficult in rea