Implantable loop recorder undersensing mimicking complete heart block

The newer implantable loop recorders recently introduced (Reveal Plus, Medtronic Inc, Minneapolis, MN, U.S.A.), equipped with auto activation capabilities, are expected to expand our diagnostic abilities in the investigation of syncopal episodes. The case presented here is that of a man with pre-syncopal and syncopal episodes, without organic heart disease, in whom the device was auto-activated due to undersensing and the recorded strip imitated complete heart block. Increased attention should be given by the interpreter of the device's recordings to avoid false positive diagnoses that might lead to serious therapeutic actions. (C) 2002 Published by Elsevier Science Ltd on behalf of The European Society of Cardiology.