A sudden change in pacing rate: Normal or malfunction?

A woman with a dual-chamber pacemaker was examined for recurrent chest discomfort and palpitations at our hospital. The Holter monitor test recorded recurrent episodes of a sudden increase in pacing rate from 60 to 105 bpm, which corresponded to the symptoms. Orthodromic pacemaker-mediated arrhythmia (OPMA), caused by ventricular lead dislodgement and atrial far-field sensing, caused the recurrent episodes of a sudden change in pacing rate. The occurrence of OPMA may represent a rare but noteworthy pacemaker problem. To our knowledge, our study reports the first case of PMA that only occurs, and is maintained, in the DDI mode.