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In 1964, Gordon Moe described the multiple wavelet hypothesis [1] based upon a computer model and proposed that the following factors-size and mass of the tissue, conduction velocity as well as refractory periods all modulated the ability to sustain atrial ~brillation. The probability of sustenance was proportional to the number of simultaneous wavelets. Later experimental data from Allessie et al provided evidence of the reentrant nature of this arrhythmia with the estimation that only 4 to 6 simultaneous wavelets were suf~cient to maintain AF in their model [2]. Intraoperative mapping studies from Cox’s group con~rmed the _eeting nature of wavelets both in time and location, precluding the use of mapping to guide ablative surgical therapy [3]. In contrast, however spatial disparities of complex electrical activity have been reported recently in both atria during AF. Li et al reported a disorganization of atrial electrograms on the posterior wall in both atria (“type III AF”) which reorganized anteriorly towards a type I AF [4] while Jais et al found that trabeculated regions in the right atrium exhibited temporally less frequent complex electrograms in comparison to the smooth walled region extending till the crista terminalis. In particular, electrograms recorded from the majority of the left atrium were complex except near the appendage again a trabeculated region (Fig. 1). Shah et al explored the electrical activity of great veins derived from atrial muscle ~bers in the venous walls. A spike like activity recorded from the superior vena cava was dissociated in 14 and followed the right atrial activity in one out of 15 patients during AF [6]. In contrast, activity in the pulmonary veins (notably the superior ones) could be recorded up to 5 cm inside and could track the left atrial activity at a high rate thus indicating a better coupled interface with the LA.