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CI-524-03 INAPPROPRIATELY DELAYED THERAPIES FOR VENTRICULAR ARRHYTHMIAS IN BIOTRONIK IMPLANTABLE CARDIOVERTER DEFIBRILLATORS

      Background

      Implantable cardioverter defibrillators (ICD) are typically programed with multiple treatment zones and discriminators to minimize inappropriate therapies for supraventricular tachycardia while still delivering life saving therapies for ventricular tachycardia (VT) and fibrillation (VF). Biotronik ICDs freeze the VT counters when tachycardia is in the VF zone due to lack of discriminators in the VF zone, which may result in an inappropriate delay in tachycardia detection.

      Objective

      To assess the incidence of inappropriately delayed therapies for ventricular arrhythmias in Biotronik ICDs.

      Methods

      Patients with Biotronik ICDs were identified from four Veterans Affairs facilities. Patient information and device tracings for patients with transmission for any (i.e. appropriate or inappropriate) ICD therapies were examined to assess for delayed tachycardia detection.

      Results

      Among 52 veteran patients with Biotronik ICDs, 7 (13%) experienced ICD therapy. Four patients had ICD therapy for ventricular arrhythmias, two of whom experienced an inappropriate delay in VT/VF detection due to the tachycardia rate oscillating between the VT and VF treatment zones. One ICD was an Acticor 7 HF-T QP cardiac resynchronization therapy ICD with a VT treatment zone at 188 beats per minute (bpm) and VF treatment zone at 240 bpm. The delay in tachycardia detection due to suspension of the VT counters during VF was 10 seconds with an overall VF time of 31 seconds before ICD shock (figure). The other was an Intica 7 VR-T DX with a VDD right ventricular (RV) lead (RV lead with atrial sensing) with a VT treatment zone at 171 bpm and VF treatment zone of 214 bpm with a tachycardia detection delayed by 1.6 seconds due to oscillation between the VT and VF treatment zones.