We have concerns with the updated adaptive servo-ventilation (ASV) recommendations1 against the use of ASV to treat moderate-severe central sleep apnea (CSA) in congestive heart failure (CHF) patients with LVEF ≤ 45%. The updated recommendation is based exclusively on the SERVE-HF study,2 which reported increased cardiovascular and mortality risk in CHF patients with LVEF ≤ 45%. However, that study found no difference in primary endpoint or cardiovascular mortality among those with LVEF ≥ 30%, and that ASV lowered risk in patients with LVEF ≤ 45% and Cheyne Stokes respiration (CSR) < 20% of recording time.
Despite being a large randomized controlled trial, critical limitations should be considered given many other studies with ASV in CHF which show improved oxygenation and measures of cardiac function. Study flaws include protocol violations with LVEF 10–54% in the ASV arm and 9–71% in the control arm. There was missing LVEF data in 130 patients in ASV arm and 126 patients in control arm. A total of 251/666 patients dropped out of the ASV arm, and 87/659 control patients used ASV.
Adequate titration was not achieved in an unknown number of patients, with mean residual AHI at 36 months of 7 (range 0–61) and mean SpO2 < 90% of 19 minutes (range 0–291). It is possible the increase in mortality was in those patients having poor control of hypoxia and/or AHI. It is possible control patients had more aggressive CHF treatment to control sleep symptoms. More ASV patients were on antiarrhythmics at baseline, which may have affected endpoints. CAN-PAP trial3 sub-analysis showed that CHF patients with optimal response to CPAP had improved outcomes. It is possible there might be a similar case with ASV.
Sixty percent of residual events were obstructive. If EPAP level is inappropriately titrated, ASV rapidly increases pressure support in response to residual obstructive events often resulting in pressure cycling. Once the airway opens, high pressure may cause overventilation exacerbating instability. Residual events and low oxygen levels may harm the patient. Newer ASV algorithms allow for automatic EPAP adjustment to obstructive events and a quicker drop in PS to as low as 0, which may limit these effects.
There is an ongoing multicenter cohort study (FACE) of ASV in CHF patients finding no difference in adverse events at their interim analysis.4 Future studies should allow a titration period to achieve optimal settings prior to randomization.
ResMed ASV helps stabilize CSR by adjusting inspiratory pressure to achieve a goal ventilation based on recent ventilation weighted toward the last 3 minutes.5 ASV benefits patients without CHF with OSA and treatment emergent CSA or baseline CSR and CHF patients with LVEF ≤ 45% with treatment-emergent CSA. Until we have more data, warnings against ASV should be changed to ASV may be considered with caution and close monitoring for patients who have LVEF < 30% and CSR > 20% of the time. Close follow-up and monitoring should be done in all patients with ASV to ensure stable cardiac status and AHI < 5 and oxygen saturations above 90%.
DISCLOSURE STATEMENT
The authors have indicated no financial conflicts of interest.
CITATION
Johnson KG, Johnson DC. ASV in CHF recommendations too restrictive. J Clin Sleep Med 2016;12(9):1313–1314.
REFERENCES
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