0623 Effect of Hypoglossal Nerve Stimulation on Hypoxic Burden and Heart Rate Response: Preliminary Results from a Randomized Crossover Trial

Introduction The cardiovascular outcomes of hypoglossal nerve stimulation (HGNS) therapy for obstructive sleep apnea (OSA) are unknown. Sleep apnea-specific hypoxic burden (HB) and heart rate response (ΔHR) have been shown to better predict cardiovascular outcomes in OSA compared to apnea-hypopnea index (AHI). We present preliminary results from the first randomized trial to examine the effects of HGNS on HB and ΔHR. Methods In our ongoing randomized crossover trial, participants undergo two study phases lasting 2 or 4 weeks each of active HGNS (HGNS-on) and HGNS withdrawal (HGNS-off). All participants have been stabilized on HGNS for >3 months and have met Sher20 surgical success criteria. During the last week of each study phase, home sleep testing is conducted. Primary outcomes are HB and ΔHR. Secondary outcomes include AHI (using a 4% hypopnea criteria) and oxygen desaturation index. HB and ΔHR are calculated per methods previously described by Azarbarzin et al. Data from 9 participants (7 male) were available for the present analyses. Signal analyses were performed in MATLAB (MathWorks). Paired t-tests were used to compare data between phases. Results Participants had a mean age of 64.7±5.0 years and BMI 27.3±2.8 kg/m2. Compared to HGNS-off, HGNS-on reduced AHI from 27.4±9.6 to 15.2±8.0 events/h (p< 0.001) and oxygen desaturation index from 24.4±9.1 to 11.5±7.2 events/h (p=0.001). HGNS significantly reduced mean HB from 73.9±51.1 to 31.8±31.6 (% min)/h (p=0.01). ΔHR decreased from 9.5±4.5 to 7.3±3.9 beats/min (p< 0.01) and event duration, from 27.4±5.8 to 22.4±6.1 s (p< 0.01). There were no significant differences in mean saturation per event (92±2% during both HGNS-on and HGNS-off, p=0.56) or magnitude of desaturation (3±1% during HGNS-on versus 4±1% during HGNS-off, p=0.28) between phases. Total sleep time also did not differ between phases (p=0.11). Conclusion Preliminary results from an ongoing randomized crossover trial of HGNS patients demonstrate reductions in HB and ΔHR with HGNS. These preliminary findings suggest that HGNS may favorably modify cardiovascular risk profiles in patients with OSA. Support (if any) This work is funded by the American Heart Association.