Background and purpose Saline-irrigated radiofrequency ablation (RFA) for atrial fibrillation (AF) is limited by the absence of reliable thermal feedback limiting the utility of temperature monitoring for power titration. The DiamondTemp (DT) ablation catheter was designed to allow efficient temperature-controlled irrigated ablation. We sought to assess the 1-year clinical safety and efficacy of the DT catheter in treating drug-refractory paroxysmal AF. Methods The TRAC-AF trial (NCT02821351) is a prospective, multi-center (n = 4), single-arm study which enrolled patients with symptomatic, drug-refractory, paroxysmal AF. Using the DT catheter, point-by-point ablation was performed around all pulmonary veins (PVs) to achieve PV isolation (PVI). Ablation was performed in a temperature-controlled mode (60 degrees C, max 50 W). Acute and chronic efficacy and safety was evaluated. Results Seventy-one patients (age 69.9 +/- 11.0 years; 60.6% male) were ablated using the DT catheter. The mean fluoroscopy and RF ablation times were 9.3 +/- 6.1 min and 20.6 +/- 8.9 min, respectively. Acute isolation of all PVs was achieved in 100% of patients, and freedom from AF after 1 year was 70.6%. There were no steam pops, char, or coagulum on the catheter tip after ablation. There were few serious procedure/device-related adverse events including a single case of cardiac tamponade (1.4%) and transient ischemic attack (1.4). Conclusion This first inman series demonstrates that temperature-controlled irrigated RFA with the DT catheter is efficient, safe, and effective in the treatment of paroxysmal AF. Randomized controlled trials are ongoing and will evaluate better the role of this catheter in relation to standard RFA.