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Blog Feature

By: Richard Rosenberg, PhD on January 24th, 2019

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ASV for CSB in CHF: Where Are We Now?

I worked in neurology departments during my sleep center days. We were a friendly group and usually all had lunch together. I remember one day our chair, Nicholas A. Vick, came into the room and told us that he had just finished giving the annual neurology lecture to the newly installed emergency medicine residents. He said that he had started off with his usual question: “When is an MRI appropriate in the emergency room?” The reply from the residents: “When the patient has a head.” Hilarity ensued. Of course, some thought needed to go into the ordering of a $2,000 test. Not everyone with a head needed an imaging study. But at the same time, it reminded me of our PAP therapy mantra, which I attribute to Phil Westbrook: “When in doubt, pressurize the snout.” We had the feeling that PAP therapy, whenever used, would first do no harm. Well, partner, that ended in 2015.

The “SERVE-HF” study1 reported a statistically significant increase in death related to cardiovascular events in patients with chronic heart failure (CHF) and an ejection fraction less than 45 percent with central sleep apnea who were treated with Adaptive Servo-Ventilation (ASV) compared to those who received standard care. This led the AASM to publish a revision of a previous practice parameter2 and issue the following recommendation: “Adaptive servo-ventilation (ASV) targeted to normalize the apnea-hypopnea index (AHI) should not be used for the treatment of CSAS related to CHF in adults with an ejection fraction ≤ 45% and moderate or severe CSA predominant, sleep-disordered breathing. (STANDARD AGAINST).”

I like to put the responses to this publication and the practice parameter change into three groups: 1) There must be something wrong with the study because ASV works in these patients; 2) there is benefit in the Cheyne-Stokes breathing pattern in these patients, and eliminating it with ASV is bad for patients; and 3) I don’t know what’s going on, but all I know is that keeping patients with CHF and ejection fractions less than 45 percent on ASV is going to get me sued so I’m not doing it any more.

Group 1 says that ASV eliminates or markedly reduces AHI in these patients and also increases ejection fraction. They also like to say that the results of the SERVE-HF study are specific to the population studied and the device used.3 The AASM agrees with the population part of that and states: “the results from this singular study cannot be generalized to other types of heart failure, i.e., those with preserved ejection fraction (EF > 45%), mild sleep-disordered breathing, or those with obstructive sleep apnea (OSA)-predominant SDB.”2 This is taken to mean that those patients who did not meet criteria for inclusion in the SERVE-HF study can continue to use ASV. The Group 1 proponents point out that ASV devices are all different and the ones used in the SERVE-HF study are no longer in use.3 But here, the AASM recommendation is: “until further data are available, other ASV devices (should) not be prescribed for the subgroup of heart failure patients with an ejection fraction ≤ 45% and moderate or severe central sleep apnea.”2

At the same time, it is reasonable to think that we may be too aggressive in pressurizing all of the snouts. The Group 2 position also draws on the SERVE-HF study, which shows that mortality was lower in “standard of care” subjects than in the ASV group. Despite correlations between CSB and mortality, at least one author describes CSB as having “physiological features more likely to be compensatory and beneficial than injurious in HF.”4

Most sleep clinicians probably find themselves in Group 3. The Case of the Month for February exemplifies the dilemma facing clinicians. Other than ASV, the AASM recommendations for treatment of CSB include CPAP, Bi-level PAP with pacing and supplemental oxygen. But what if these don’t work? And how can you tell if they are working? What if Group 2 is correct and any method used to reduce or eliminate CSB has a negative impact? Overwhelming any available evidence is the fear that putting a patient on ASV might be the best option for the patient but lead to a lawsuit and the end of a physician’s career. How can we know what the best path is for the patient?

The answer is more data. There are probably a bunch of indicators that would help clinicians provide individualized care for patients with CHF and CSB. Some may benefit from aggressive ASV treatment, eliminating every apnea and oxygen desaturation. Others may be harmed by the same treatment. Given the mixed results available in the literature, it is likely that the population of patients with CHF and CSB is not homogenous.

I recently bought a smart watch, and shortly afterward my cellphone asked me if I was willing to participate in a study of cardiovascular variables. This kind of “big data” collection has the promise of including enough subjects with specific combinations of factors to allow us to separate patients who will benefit from certain treatments from those who will not. A study such as this would have been impossible only a few years ago, both in terms of data collection and computational power for analysis. But the future is today, and it holds the promise of real evidence-based treatment decisions in the near future.

Big data for cardiovascular analysis? I told my phone to count me in. Hopefully, you will do the same.

References

  1. Cowie MR, Woehrle H, Wegscheider K, et al. Adaptive servo-ventilation for central sleep apnea in systolic heart failure. N Engl J Med. 2015;373(12):1095-1105.
  2. Aurora RN, Bista SR, Casey KR, Chowdhuri S, Kristo DA, Mallea JM, Ramar K, Rowley JA, Zak RS, Heald JL. Updated adaptive servo-ventilation recommendations for the 2012 AASM guideline: “The Treatment of Central Sleep Apnea Syndromes in Adults: Practice Parameters with an Evidence-Based Literature Review and Meta-Analyses”. J Clin Sleep Med2016;12(5):757–761.
  3. Javaheri S, Brown LK, Randerath W, Khayat R. SERVE-HF: More questions than answers. Chest 2016:149(4) 900 – 904.
  4. Naughton, M. (2012). Cheyne–Stokes respiration: Friend or foe? Thorax, 67(4), 357-35760.