BIOMONITOR III sensing dependency on Body Mass Index (BMi3 Study): Preliminary results

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): BIOTRONIK SE & Co. KG BACKGROUND: Published data on commercially available implantable cardiac monitors (ICMs) and the influence of body mass index (BMI) on the devices sensing performance are scarce. The BIOMONITOR III is an ICM equipped with a large sensing vector allowing to detect high quality subcutaneous ECG (sECG) signals. PURPOSE: To evaluate the sensing performance of BIOMONITOR III in two groups of patients (pts) with different BMIs: the first group with BMI>30 (group A) and the second group with BMI<20 (group B). METHODS: The BMi3 is a multicentre, prospective, non-randomized, observational study. The ICM data collection was performed at the implantation and then at 10-days and 3-month follow-up (f-up) visits. A patient questionnaire was conducted at each f-up. The primary end-point was an average R-wave amplitude at f-up end > 0.5 mV in both groups. RESULTS: A total of 15 pts were included, 10 in group A (8 males, BMI 35.8±3.9) and 5 in group B (2 males, BMI 18.2±1.3). The main implant site was along the heart axis at 45° (70% of pts in group A and 60% of pts of group B), followed by a left parasternal position. The average R-wave amplitude was > 0.5 mV at implant and at each f-up in both groups without significant differences between the groups (see Figure). The P-wave was visible on sECG in all group B pts and in 80% of group A pts. At 3-month f-up the noise burden (detected over the previous 24-h) was 2.6±1.8% in group A vs. 0.0% in group B (p=0.005). Device extraction was performed at the end of the study in 2 pts because of device migration associated to pending erosion (1 pt, group A) or discomfort (1 pt, group A), documented at the 3-months f-up. Overall, the device comfort was reported as "good" or "very good" by 89% of pts in group A vs. 67% of pts in group B (p = ns). CONCLUSIONS: In the BMi3 study the BMI does not significantly affect the R-wave amplitude which remained stable and satisfactory during f-up in both groups. Conversely P-wave visibility on sECG can be reduced in obese pts. Noise is more frequently detected in BMIs > 30 presumably because of difficulties in reaching an implant site allowing minimal device movements in these specific cases. Finally, both skinny and obese pts seem to be a higher risk to experience device migration compared to standard population but larger studies are required to confirm these preliminary observations. [Figure: see text]