In the context of chronic atrial fibrillation (AF) ablation, substrate modulation has demonstrated its efficacy and its positive impact both into conversion of the AF either directly to sinus rhythm (SR) or to atrial tachycardia (AT) and into SR maintenance. However, substrate modulation, which can be performed either by linear lesions deployment or/and by targeting complex and fractionated atrial electrograms (CFAEs), can be a difficult task. We present a safe and non time-consuming technique conceived in our center which we think is of interest for substrate modulation purpose in the AF ablation framework. This technique named the "clockwise loop approach" may permit both extensive and accurate mapping of a great amount of the LA and facilitation of LA linear lesions deployment.