Ablation of Persistent Atrial Fibrillation Using Multielectrode Catheters and Duty-Cycled Radiofrequency Energy - Scharf,C; Boersma,L; Davies,W; Kanagaratnam,P; Peters,NS; Paul,V; Rowland,E; Grace,A; Fynn,S; Dang,L; Oral,H; Morady,F (JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY, 2009)