2. Air Versus Oxygen in ST-Segment
Elevation Myocardial Infarction
AVOID Study
Published in Circulation. 2015 Jun
16;131(24):2143-50. doi:
10.1161/CIRCULATIONAHA.114.014494. Epub
2015 May 22
by Stub et al
3. Background
Oxygen therapy commonly used in initial
treatment in STEMI – MONA
Morphine
Oxygen
Nitrates
Aspirin
There are a little evidence that suggest oxygen
may do more harm than good
Cochrane review in 2013 conclusion: no
conclusive evidence – suggest an RCT
4. Clinical Question
Among normoxic patients with STEMI, does
supplemental oxygen therapy vs no supplemental
oxygen therapy increase myocardial infarct size?
5. Design
Multicenter, randomised, open label, randomised
N = 441
Oxygen (n=218)
No oxygen (n=223)
Setting: 10 centers in Melbourne, Australia (24 hr PCI
center)
Enrollment: October 2011 till July 2014
Follow up: 6 months
Analysis: Intention to treat
Powe : Witholding O2 may influence myocardial injury by
20%, α-level set at 0.01
6. Population
Inclusion Criteria
≥ 18 yr old
Chest pain <12 hours
Prehospital ECG –
STEMI
Exclusion Criteria
SpO2 < 94%
Bronchospasm
requiring neb with O2
O2 prior to
randomisation
Altered conscious
state
Transport to non
studied hospital
7. Intervention
Facemask 8L/min – continued until transfer to
cardiac care ward
Control
No oxygen unless O2 fell below 94% - NC
4L/min or Facemask 8L/min
Both groups initiated on aspirin 300mg by paramedics
8. Results (Primary)
Geometric Mean Peak Trop I
Oxygen 57.4 mcg/L
No Oxygen 48 mcg/L (p=0.18)
Geometric Mean Peak CK
Oxygen 1948 U/L
No Oxygen 1543 U/L (p=0.01)
9. Results (Adverse Events)
Death by Hospital Discharge
Oxygen 1.8%
No Oxygen 4.5% (p=0.11)
Recurrent MI
Oxygen 5.5%
No Oxygen 0.9% (p=0.006)
NNH = 21
Major Cardiac Arrthymia
Oxygen 40.4%
No Oxygen 31.4% (p=0.05)
10. Results (CMR)
32% underwent CMR
Oxygen 65
No Oxygen 74
Median Infarct Size
Oxygen 20.3g
No Oxygen 13.1g (p=0.04)
% Infarct of LV
Oxygen 12.6%
No Oxygen 9.0% (p=0.08)
11. Conclusion
In normoxic patients, routine O2 administration
was
not associated with reduction in symptoms
accompanied by harm as reflected by
significant CK rise
larger infarct size by CMR at 6 months
12. Questions
Does the primary outcome reflects infarct size?
Does infarct size reflects clinical outcome?
What are the current guidelines on STEMI
regarding oxygen supplements?
What are your practices with STEMI or even NSE-
ACS?
Assuming the conclusion of the study is not a
Type I error, how can you explain in terms of
pathophysiology
13. Questions
Does the actual PaO2 matters?
Are you convinced after this paper regarding
switching of practice of not giving routine oxygen
supplementation?
14.
15. Questions
What is the primary outcome of this study? Do
you think this is appropriate?
What is intention to treat analysis? Give two
advantages and two disadvantages of this method
of analysis.
At the end of this journal club, Dr Jo Mower asks
you whether it should be introduced in your
department. Give reasons to support your stand.
16. THANK YOU
Thank Prof for editing the slides
Next Journal Club on 9 September 2015
Feedback on how to improve journal club
