Atrial fibrillation (AF) is the most common arrhythmia in clinical practice, accounts for one-third of arrhythmia hospitalizations and is associated with an increased risk of stroke, heart failure, and all-cause mortality. Moreover, there is an increasing AF prevalence due to aging of the population, a rising prevalence of chronic heart disease, and increased survival. Unfortunately, medications aimed at suppressing AF and maintaining sinus rhythm or at controlling ventricular rate are only marginally effective and may cause serious adverse effects. The limitations of pharmacologic treatment patterns have fuelled the development of new interventional strategies. Current techniques of AF ablation can achieve a 60-80% improvement in highly selected patients with medically refractory AF. However, the procedure is not without risk, is long-lasting and recurrence rates are still high. Moreover, the results in persistent AF patients are far from optimal, require the creation of extensive atrial lesions and repeated procedures. The main reason that explains the current situation is the incomplete understanding of mechanisms underlying AF maintenance despite many years of research and speculation. The incremental value of ablation of high frequency sources following circumferential PV isolation has not been assessed. There is no prospective data available as to the safety and benefit of such a combined approach in patients with paroxysmal and persistent AF. Such information would be very important in helping guide the future direction of ablative therapy for AF as well as helping to answer important questions about the role of high frequency sites in persistent AF treatment.