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Figure 1 Spontaneous atrial tachycardia (AT) to atrial fibrillation (AF) transition preceded by fractionated activity in the right inferior pulmonary vein (RIPV). Asterisks separate AT from AF. CL = cycle length; I = surface ECG lead I; LAA = left atrial appendage; LIPV = left inferior pulmonary vein; LSPV = left superior pulmonary vein; RSPV = right superior pulmonary vein.