A Prospective Study Comparing the Sensed R Wave in Bipolar and Extended Bipolar Configurations: The PropR Study

Background Progress in implantable cardiac defibrillator (ICD) technology has allowed for switching the sensing polarity for the detection of ventricular fibrillation (VF). However, whether one sensing polarity confers additional advantage over the other is not known. Objectives To determine whether one sensing polarity is superior to the other for the detection of VF. Methods Patients were enrolled into a prospective randomized study of sensing of VF and R waves in normal rhythm. Sensing of VF was determined by number of under sensed beats (USB), and time to detection of VF (TDVF). Each patient underwent ICD implantation followed by testing of the ICD. At each induction, patients were randomized to sensing in extended bipolar (EBP) or true bipolar (TBP) configuration. Additionally, R waves were compared at implant and at 1-month follow-up. Results A total of 50 patients were enrolled into the study. When evaluating the primary endpoint, no difference was found between USB in EBP or TBP configuration; 1.1 ± 1.2 beats versus 1.3 ± 1.3 beats; P = NS. Also, no difference was found between TDVF in EBP or TBP configurations; 5.9 ± 0.6 seconds versus 5.9 ± 0.6 seconds; P = NS. With regard to the secondary endpoints, there was no difference between R waves in EBP or TBP configurations at the time of implant 10.9 ± 4.8 mV versus 10.9 ± 4.8 mV P = NS; or at 1-month follow-up 12.4 ± 4.7 mV versus 12.0 ± 5.4 mV P = NS. Conclusions There is no difference in the detection of VF between EBP or TBP configurations in patients undergoing ICD implantation.