Dual zone programming reduces inappropriate S-ICD shocks

Dual zone programming reduces inappropriate S-ICD shocks

Dual zone ICD programming: Inappropriate shocks are an important adverse effects of life saving implantable cardioverter defibrillators (ICD). Subcutaneous ICDs with no intra cardiac leads (S-ICD) are not immune from this adverse effect. A new algorithm to reduce inappropriate shocks by programming two zones – one shock zone and another with an arrhythmia discrimination algorithm at lower rates (conditional shock zone programming). Michael R Gold, Raul Weiss, Dominic A M J Theuns, Warren Smith, Angel Leon, Bradley P Knight, Nathan Carter, Michael Husby and Martin C Burke showed that adding an additional zone with arrhythmia discrimination reduces the inappropriate shocks from about twenty six percent to around ten percent in a study involving about three hundred patients over two years [1]. There was no difference in the freedom from appropriate shocks between the groups, nor there was a difference in the mean time to appropriate therapy. It is noteworthy that there was no increased incidence of syncope with dual zone therapy. There was only one episode of arrhythmic syncope in the cohort.

Usual programming has only a single zone for giving shocks based strictly on heart rate criteria without any rhythm discrimination. In the conditional shock zone, rhythm discrimination algorithm can classify rhythms which needs a shock vs those that do not need shock when it is deemed to be supraventricular.

Reference

1. Michael R Gold, Raul Weiss, Dominic A M J Theuns, Warren Smith, Angel Leon, Bradley P Knight, Nathan Carter, Michael Husby, Martin C Burke. Use of a discrimination algorithm to reduce inappropriate shocks with a subcutaneous implantable cardioverter-defibrillator. Heart Rhythm. 2014 Aug;11(8):1352-8.