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Atrial Selective Effect of Amiodarone to Increase Threshold of Excitation


Address for reprints: Juan Manuel Grande, M.D., Severo Ochoa Hospital, Department of Cardiology, Avenida de Orellana s/n, 28911 Leganés, Madrid, Spain. Fax: 0034 91 481 85 00; e-mail:


Increases of pacing threshold stimulation are well documented with different antiarrhythmic drugs, but not with amiodarone. We report a case of a patient with dual-chamber pacing, with stable thresholds on repeated measurements on the last year, who presented severe increase of atrial pacing threshold resulting in loss of atrial capture after a year of treatment with amiodarone. Thresholds were normalized once amiodarone was removed. Ventricular thresholds were not affected.