Javaheri, Shahrokh

Abstract Introduction Despite AASM scoring guidelines encouraging classifying hypopneas as central or obstructive, classification is underutilized in practice. However, without that effort patients may receive an incorrect primary diagnosis and suboptimal treatment. The remedē® System Pivotal Trial studied transvenous phrenic nerve stimulation (TPNS) to treat adult patients with moderate to severe central sleep apnea (CSA). Entry criteria required apnea hypopnea index (AHI)≥20 with the central apnea index (CAI) greater than the obstructive apnea index and obstructive apneas< 20% of AHI but did not consider hypopnea differentiation. This analysis re-examined sleep studies from the trial to assess how hypopnea classification might lead to better patient selection for this therapy. Methods Hypopneas were classified as central versus obstructive by a sleep core laboratory following a modified version of AASM recommended criteria. The AHI composition was assessed at baseline and after 6 months of therapy. Results At baseline, 91% (138/151) of patients had ≥50% of events classified as central when accounting for hypopnea classification. If all hypopneas were assumed to be obstructive, only 63% (95/151) would have had ≥50% central events. Additionally, 95% (144/151) of patients had central AHI ≥15/hour, compared to 73% (110/151) with a central apnea index (CAI) ≥15/hour. The likelihood of achieving a ≥50% AHI reduction increased with the percentage of baseline events that were central: responder rates were 37.5% for patients with < 50% central events at baseline, incrementally increasing to 76.5% for those with ≥90% central events. At 6 months, the residual AHI predominantly consisted of obstructive events. Central events decreased by 89% with treatment, from a baseline median of 32/hour [1st and 3rd quartiles: 22, 50]. Obstructive apneas rose by 2/hour and obstructive hypopneas increased by 2/hour from a baseline median of 5 obstructive events/hour [2, 12]. Conclusion Distinguishing central from obstructive hypopneas is required to accurately determine if a patient has central sleep apnea/Cheyne Stokes respiration, and is crucial for epidemiologic studies, appropriate therapy selection, and managing patient expectations about treatment outcomes. This analysis suggests that accurate hypopnea classification may prevent disqualification of patients who could benefit from TPNS therapy, which effectively treats central sleep apnea syndrome. Support (if any) ZOLL Respicardia, Inc.