Current recommendations for pacemapping are based on expert opinion and animals models. Present study sought to evaluate the influence of different parameters of pacemapping on QRS morphology. Pacemapping is performed with different cycle length (fixed burst vs. coupling interval) and stimulation output (maximum output vs. threshold) and resulting QRS complexes are compared to clinical PVC and the standard of care to determine the optimal parameter setting in pacemapping.

Pacemapping is a common technique to determine to origin of ventricular ectopy during catheter ablation of premature ventricular contractions (PVC). During the pacemapping process an electrical pacing stimulus is applied via the ablation catheter and the resulting QRS complex is compared the clinical target PVC. The higher the consistency between the stimulated QRS complex and the clinical PVC, the nearer the catheter is located to the origin of ectopy.

Current recommendations for the execution of pacemapping are based on expert opinion and animals models. The investigators sought to assess for the first time in a clinical real life setting the different parameters for pacemapping (i.e. Cycle length and stimulation output). Therefore during the pacemapping process in routine PVC ablation pacing is performed with different cycle length (fixed burst vs. coupling interval of PVC) and different electrical output (maximum output vs. stimulation threshold). The resulting QRS morphologies are on the one hand compared to the ablation target (clinical PVC) and on the other hand to the suggest standard of care (Coupling interval at pacing threshold) to determine the optimal setting of parameters in pacemapping.

Inclusion Criteria:

• All patients undergoing PVC ablation

Exclusion Criteria:

• patients <18 years
• patients not able to consent
• pregnancy
• contraindication for PVC ablation
• unavailability of vascular access
• patients with complex congenital heart disease
• expected hemodynamical instability during pacemapping