Pii: S1010-7940(99)00361-9

We use cryoablation as the treatment of choice for AF (atrial ®brillation): the technique consists of a linear cryoablation at 2608C connecting the four pulmonary veins and the posterior mitral lea ̄et. Incomplete ablation of atrial myocytes may be responsible for AF recurrence should cryoablation be incomplete (i.e. non-transmural) because of associated atrial hypertrophy [1]. In fact should any electrical path be spared, because of incomplete myocyte necrosis, the anomalous circuit could perpetuate in spite of the surgical treatment. For this reason we decided to evaluate in humans the acute and chronic histological modi®cations and the severity and the extent of the myocyte damage taking place in the atrial wall after cryoablation [2]. In four consecutive patients, operated on for mitral surgery, an atrial biopsy (1 cm) was taken from the right (two patients) or left (two patients) appendage once the heart was, respectively, canulated or already under cardioplegic arrest during cardiopulmonary-bypass (CPB) at moderate hypothermia. These locations were chosen because they are easily accessible and they would have European Journal of Cardio-thoracic Surgery 17 (2000) 339±340