SDB is a general term used to describe various different
abnormalities in breathing pattern which occur during sleep,
including obstructive and central sleep apnea. Obstructive
sleep apnea (OSA) is a common disorder which affects rough-
ly 10% of the US population and approximately 1/3 of people
with congestive heart failure. OSA patients have reductions
or stoppages in airflow despite ongoing respiratory efforts. In
contrast, central sleep apnea (CSA) patients have reductions
or stoppages in airflow without respiratory effort. Cheyne
Stokes respirations (CSR) is a special form of CSA which is
seen in roughly 1/3 people with congestive heart failure. OSA
and CSA sometime occur in the same individuals either at dif-
ferent times of the night or from one night to the next. Thus,
the term SDB is used to refer to both OSA and CSA together
since the distinction is sometimes hard to make.
Most, but not all, studies suggest that heart failure patients
with SDB have worse prognosis than matched heart fail-
ure patients without SDB. This means they can have more
symptoms and poorer health and disease control. Patients
with either OSA or CSA are thought to be at risk of increased
mortality and risk of hospitalizations. There have been some
theories suggesting that CSR may be beneficial for certain pa-
tients, but this view has not been widely accepted by experts.
What is the new medical research study called
SERVE-HF all about?
Results of a new medical research study were reported at
the recent American Thoracic Society medical conference
in May 2015 in Denver CO. The study involved over 1300 pa-
tients with CHF and CSA along with a specific type of heart
problem (impaired left ventricular systolic function, ejection
had some concerning findings. The study was a randomized
paring adaptive servo-ventilation (ASV) with usual medical
therapy. The primary outcome was a composite measure of
either mortality or unplanned hospitalization which showed
no difference between groups. Of note, sudden cardiac death
was more common in the ASV group as compared to the
medical therapy group (10% vs. 7.5%, p<0.05); this difference
was considered to be not likely due to chance alone. Experts
are currently not clear why this risk occurred. Based on this
finding, patients who are using ASV are advised to talk with
their health care provider about stopping it.
Should I stop my ASV?
It depends, talk to your health care provider. Many patients
have received ASV for other reasons that were not studied
in the SERVE-HF study. For example, ASV has been used for
complex sleep apnea (treatment emergent central apnea),
narcotic induced central apnea, SDB in people with CHF with
preserved ejection fraction. There is no good reason at this
time to stop using ASV for these conditions. For patients
who have a new diagnosis of CSA with impaired left ventricu-
lar systolic function, we would not recommend starting ASV
at this time. For patients with CSA and CHF with reduced
ejection fraction, we believe the decision needs to be
individualized in communication with your specialist. Some
patients feel much better on ASV and are willing to take a
small potential risk of sudden cardiovascular death because
of their improved quality of life from ASV. Some patients
who are struggling with ASV may be very willing to give it up,
since they may not be using it very much in the first place.
For patients who are on ASV with CHF, a careful medical
evaluation would be worthwhile. Optimization of medical
therapy would be beneficial since withdrawing ASV abruptly
may also have risks, particularly in patients whose condition
is not controlled optimally. In some cases, transitioning pa-
tients from ASV to standard CPAP could also be considered.
For example, patients who have never been on CPAP who
have OSA may not need ASV and in such cases transition-
ing to CPAP would seem reasonable. In patients who have
previously failed CPAP, ASV withdrawal could be considered,
Use of Adaptive Servo-ventilation (ASV) for People
With Heart Failure and Trouble Sleeping
People with heart failure often have trouble breathing
while asleep. Studies have shown that roughly 2 out of
every 3 patients with heart failure will have some sort
of breathing problem while asleep (known as sleep
Am J Respir Crit Care Med Vol. 192, P1-P2, 2015
ATS Patient Education Series © 2015 American Thoracic Society
although the optimal management of these patients remains
unclear. Treatment options such as oxygen and medicines
that help the body clear extra fluids, such as acetazolamide,
could be alternatives you can discuss with your health care
provider. Careful monitoring of electrolytes, such as potassi-
um and magnesium levels, would also seem reasonable. Talk
to your specialist before you decide what to do.
The findings of this new study were unexpected and thus
experts have been discussing why this finding might have
1. The possibility exists that the findings were by chance
(bad luck) and that more studies will be needed before
we can believe that ASV is really harmful. Sometimes
imbalances occur at randomization such that one group
is sicker than the other by chance and thus the poor out-
comes may relate to patient characteristics rather than a
real effect of the ASV therapy.
2. There may be direct effects of ASV which could affect
breathing pattern or heart function, although standard
CPAP has similar effects and is not thought to carry the
same risks. The ASV settings can sometimes lead to
hyperventilation (breathing too much) which can lead to
respiratory alkalosis (low carbon dioxide, high pH in the
body) and could have associated electrolyte abnormali-
ties (such as potassium level). These metabolic changes,
if present, could trigger arrhythmias which can lead to
sudden cardiac death.
3. Another possibility is indirect effects of ASV. For example,
changes in medications or health behaviors can occur
in any un-blinded study which can be important. For
example, if patients stop taking their medications, or start
excessive daily activities abruptly, or the doctor changes
their medications, these effects could be problematic at
least for some patients.
Because the details are unclear, we do not know exactly
why cardiac sudden death occurred in some patients on ASV
therapy. We have speculated here, but await further data.
What if I have a different brand of ASV machine?
Several companies make ASV machines including ResMed,
Philips Respironics etc. The SERVE-HF study involved the
ResMed ASV machine (adaptive servo-ventilation). Philips
Respironics released a statement suggesting their device
(auto servo-ventilation) is likely to have similar effects to
that of ResMed given that the algorithms are similar. Thus,
the type of device probably does not make a major differ-
ence from the standpoint of what is recommended.
I have heart failure and don’t feel great—should I see
a sleep or lung specialist at this point?
Yes, the new findings suggest we need to be cautious about
treating CSR, but there are still many contributors to sleepiness
and fatigue that are common in heart failure which your health
care provider can address. For example, insomnia, leg move-
ments, obstructive sleep apnea, and other factors may contrib-
ute to feeling poorly and should still be identified and treated.
I am on PAP (CPAP or APAP) but don’t have heart
failure, am I OK?
The new findings relate only to patients with congestive
heart failure with impaired left ventricular function. Obstruc-
tive sleep apnea remains an important disease with import-
ant effects on health. You should continue CPAP therapy as
it should make you feel better and may protect your heart.
APAP (auto-titration PAP) is not related to ASV and thus
there is no cause for concern based on the new findings.
Atul Malhotra, MD.
Marianna Sockrider MD, DrPH
bution to the Glossary of Terms
This information is a public service of the American Thoracic Society.
The content is for educational purposes only. It should not be used as a substitute
for the medical advice of one’s health care provider.
Glossary of Terms
Congestive Heart Failure—a build-up of fluid in the body
due to the heart not working well
tients are randomly assigned to one treatment or another
the patients and researchers know which treatment they
Field safety notice—medical care notice sent out to health
care providers and institutions about a safety issue
combines two or more measurements
medicine(s) or other treatment to help a person manage