INTRODUCTION: The tissue temperature-controlled DiamondTemp ablation (DTA) catheter has been mainly used for atrial fibrillation ablation. We report our initial experience in using this catheter for the treatment of outflow premature ventricular contractions (PVCs) or repetitive non-sustained monomorphic ventricular tachycardias (VTs). METHODS: Twenty patients were studied: 10 with right ventricular outflow tract PVCs/VTs, eight with PVCs/VTs from the aortic sinus cusps, and two with left ventricular outflow tract PVCs. The DTA parameters were adjusted to a target-temperature of 60°C with 50 W power. Ablation success was defined as the absence of clinical VT/PVCs at the end of the procedure and during the next 48 h of continuous rhythm monitoring without antiarrhythmic drugs. All patients were reevaluated 2 months after the ablation. RESULTS: The average ablation duration was 262 (145-690) seconds and the average tissue temperature (T) was 50.4 ± 2.9°C. A mean number of 11 ± 6 lesions per case were applied. The average time of T >
50°C was 18 (12-20) seconds, that is 70% of the ablation time, and an average relative impedance drop of 13.8 ± 2.0% was recorded. No serious complications occurred, and no VT recurrence was observed until discharge and during the short follow-up period. CONCLUSION: This initial evaluation suggests that the DTA system reached the adjusted temperature and power targets, and it can be effectively and safely applied for the treatment of outflow tract PVCs/VTs. This performance should be further evaluated by long-term randomized controlled trials in comparison to conventional ablation catheters.