Purpose: Wedging a circular mapping catheter (CMC) into pulmonary vein (PV) is recommended to validate their isolation during wide antral circumferential ablation (WACA). Since appropriate catheter contact has proved crucial for lesion quality, we hypothesize that a contactforce (CF) guided single catheter approach might be suitable and effective for PV isolation (PVI). Methods: With the use of a CF ablation catheter, WACA was performed for both sets of PVs in 50 patients with paroxysmal AF. Antral exit block was demonstrated by sequential pacing at 9 equidistant points within the circular WACA lesion set (including the carina), with a target force ! 10g. Sites displaying persistent left atrial capture underwent additional pacing maneuvers and electrogram analysis, in order to detect and close residual gaps. Once exit block was deemed achieved, PVI was validated by conventional CMC-based analysis. Results: The mean procedural duration, fluoroscopy exposure time, total ablation time and force applied per-procedure were respectively of 101 + 17 min, 5.6 + 2.2 min, 23.2 + 7.1 min and 17.8 + 2.6 grams. 84 of 100 PV antra were disconnected after an exclusive anatomical approach, while 16 displayed residual gaps. Of the latter, 14 were isolated with the sole CF catheter. The positive predictive value of antral exit block reached 100% for predicting PVI as assessed with CMC. Conclusions: CF-guided single catheter technique is a feasible method for PVI in patients with paroxysmal AF. This simplified approach proves as effective as the standard CMC-based approach for residual gaps identification and conduction block validation. Introduction: The impact of power, ablation time and contact force (CF) alone on lesion formation in atrial fibrillation ablation has been proven. However, the interaction and collective effect of these factors on ablation effectiveness has not been clearly elucidated. Methods: 416 ablation points were acquired from 19 patients with paroxysmal atrial fibrillation who underwent pulmonary vein isolation for the first time. The points were collected at the beginning of the procedure at separate sites to avoid the mutual effect. A Thermocool SmartTouch catheter was used for radiofrequency ablation. Energy was applied for 60 s at every site under the same power setting. All data including ablation time, power, CF and impedance were recorded on a Carto 3 system and analyzed off-line. Impedance drop (ID) was used as a surrogate for evaluating ablation effectiveness and ID ! 10V regarded as an adequate lesion formation. Data were grouped by power (25W, n ¼ 115, 30W, n ¼ 166, and 35W, n ¼ 135) and average CF (,5g, 5-10g, 11-20g and .20g) for analysis. Results: When CF was ,5g, IDs did not raise with power increase and never crossed 10V. When CF was !5g, IDs were getting higher when power or CF increased. This effect was observed from 0-40s but not after 40s. When CF over 20g and power over 30W, there was a tendency that impedance rose again. (Figure) Conclusions: When CF ,5g, ablation effect cannot be im...