Automatic rate response after mode switching

N° 26
Manufacturer Medtronic Device PM Field Programming for exercise

64-year-old man with complete atrioventricular block implanted with an Adapta pacemaker; grade II mitral regurgitation; routine control; asymptomatic patient.

Graph and trace
  1. programming in DDD mode without rate response;
  2. the atrial histogram shows that the patient has gone into persistent atrial fibrillation;
  3. the ventricular histogram shows a rate response of the paced ventricles with satisfactory distribution of the rate curves.

This patient is initially programmed in DDD mode without rate response. The maximum rate responsive frequency corresponds to the rate response occurring after mode switching due to atrial arrhythmia. The atrial histogram shows continuously high rates corresponding to atrial fibrillation (confirmed on the surface electrocardiogram). The pacemaker has switched to DDIR mode explaining the ventricular histogram showing a proper rate response (a switch in DDI mode would have led to fixed-rate pacing at the minimum rate). This interrogation of the pacemaker raises a number of questions:

  1. in this patient with a CHADS2 score of 3, anticoagulant therapy is indicated. The heart rate is well controlled due to the conduction disturbance, the patient is asymptomatic and the diagnosis of atrial fibrillation is made during a routine visit. Systematic remote monitoring should allow for much earlier diagnosis in asymptomatic patients;
  2. reduction of the atrial rhythm disorder can be proposed even if the patient is asymptomatic and the heart rate is well controlled;
  3. while a reduction strategy is preferred, the DDD mode with DDIR switching in the presence of an atrial arrhythmia appears appropriate. We can see in this patient the interest of rate response during the fallback phases with the maintenance of physiological-appearing rates both at rest and on exertion. If a rate response strategy is preferred, the presence of permanent atrial fibrillation likely justifies a programming in VVIR mode.
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