Background: With an increasing number of long and complex procedures for the treatment of ventricular tachycardia, fluoroscopy reduction plays an important role in the safety of patients, physicians and medical staff. We describe the clinical use of a novel fluoroscopyimitating 3D cardiovascular navigation system for VT ablation. Methods: 14 patients with ischemic or dilated cardiomyopathy underwent VT ablation between May and October 2012 using a 4D cardiovascular navigation system (MediGuide™). The real-time position of sensor-enabled electrophysiology diagnostic and ablation catheters were projected onto pre-recorded ventriculogram cine loops. Ablation was guided by local activation time (LAT) maps, pace maps, and substrate maps of the LV within 3D chamber geometries of the co-registered impedance base mapping technology (NavX-EnSite). Results: Ablation was performed successfully in all 14 patients. Of the 14 ablated patients, 11 (79%) were free of VT after a median followup time of 90 (IQR 60-143) days. There were no major complications, especially no pericardial effusion. Fluoroscopy time for preparation (catheter insertion, transseptal puncture, and LV angiograms) was 1.5 (IQR 1.0-5.1) min, with a dose of 2302 (IQR 1593-3131) μGy-m2. For mapping and ablation, fluoroscopy time was 0 (IQR 0-8.2) min, with a dose of 0 (IQR 0-1032) μGy-m2. In 9/14 (64%) patients lead protection was completely taken off after the preparation. Conclusions: The data describe early experience with the MediGuide™ technology in patients with VT ablation. Usage of the technology was safe and clinically effective. This preliminary data indicate a significant potential for substantial reduction of radiation exposure during such complex and lengthy interventions.