PO-01-014 IMPACT OF GENDER ON P- AND R-WAVE AMPLITUDE IN A SURFACE EKG SIMULATION STUDY FOR INSERTABLE CARDIAC MONITOR

Abstract

Cosmetic concerns or anatomic differences between males and females may influence implantation location of Insertable Cardiac Monitor (ICM). To assess device, implant and patient factors impacting electrogram sensing by proxy of precordial single-lead surface EKG recordings. 150 participants each had 12 separate tracings of single-lead surface EKG acquired using Northeast Holter (DR200/HE) placed at the parasternal 4th intercostal space to mimic ICM recordings. 3M electrodes were positioned at different vector length (75mm & 45mm) for each of three vector angles (vertical, oblique, horizontal) repeated in two postures (upright & supine). Height and weight were assessed for body surface area (BSA) calculation and impedance-based body fat percentage (BF%) was measured. All EKG strips were uploaded into DigitizeIt software for offline analysis by blinded technicians. Kruskal-Wallis test with Dunn’s multiple pairwise comparisons was performed to assess gender differences in EGM amplitudes. A total of 1,800 tracings from 150 participants [55.5% male, median age 59years (IQR 35 – 73)] were assessed. Compared to male participants, females had lower weight [73 (60 - 87) vs. 84kg (75 – 98), p<.001] but higher BF% [24.4 ± 8.8 vs. 35.2 ± 9.6%, p<.001]. There was no difference between gender for pairwise comparisons of median P-wave amplitude in each vector angle using different vector lengths (Panel A). Male participants had larger R-wave in vertical orientation for both vector lengths, but no difference for R-wave amplitude was seen for other angles (Panel B). Overall median amplitude of P-wave was 45% larger (.042 vs. .029mV, p<.001) and R-wave was 53% larger (.81 vs. .53 mV, p<.001) for vector length of 75 vs 45mm. The oblique vector angle had the largest P-wave amplitude of .038mV (.022 – .054) and R-wave of 0.76mV (0.52 – 1.08). P-wave amplitude was identical between both gender at all vector angles. Marginal differences in R-wave amplitude are noted between males and females for vertical vector only, but not with oblique or horizontal angle. Although the oblique angle had the largest P- and R-wave amplitudes, a longer sensing vector provides larger EGM amplitudes which may be important for achieving adequate electrogram sensing when ICM implant orientation is influenced by cosmetic or anatomical considerations.