Classifying hypopneas as obstructive or central can enhance transvenous phrenic nerve stimulation therapy patient selection and outcomes

Abstract

Study objectives: While not all sleep laboratories distinguish between obstructive and central hypopneas, recent research suggests that patients may receive an incorrect primary diagnosis without this effort. The remedē System Pivotal Trial studied transvenous phrenic nerve stimulation in patients with moderate-to-severe central sleep apnea (CSA). Entry criteria required apnea-hypopnea index (AHI) ≥ 20 with central apnea index greater than obstructive apnea index and obstructive apneas < 20% of AHI but did not classify hypopneas. This analysis re-examined sleep studies from the trial to assess hypopnea classification impact on candidacy and treatment outcomes.

Methods: Hypopneas were classified as central versus obstructive by a sleep core laboratory following a modified version of AASM recommended criteria. AHI composition was assessed pre/post treatment.

Results: At baseline, 91% (138/151) of patients had ≥ 50% of events classified as central accounting for hypopnea classification. If all hypopneas were assumed obstructive, only 63% (95/151) would have had ≥ 50% central events. The likelihood of achieving ≥ 50% AHI reduction increased with the percentage of baseline events that were central: responder rates were 37.5% for patients with < 50% central events, incrementally increasing to 76.5% for those with ≥ 90% central events. At 6 months, residual AHI predominantly consisted of obstructive hypopneas. Central events decreased by 89% with treatment (baseline median 32 events/h). Obstructive apneas and hypopneas increased by 2 events/h and 3 events/h, respectively.

Conclusions: Distinguishing central from obstructive hypopneas is required to accurately determine the proportion of central and obstructive breathing events, and is crucial for appropriate therapy selection and managing patient expectations about treatment outcomes.

Clinical trial registration: Registry: ClinicalTrials.gov; Identifier: NCT01816776.

Keywords: central hypopnea; central sleep apnea; transvenous phrenic nerve stimulation.