title: The bizzare phenomenon of smokers' paradox in the immediate outcome post acute myocardial infarction: an insight into the Malaysian National Cardiovascular Database-Acute Coronary Syndrome (NCVD-ACS) registry year 2006-2013.
abstract: BACKGROUND
  'Smoker's paradox' is a controversial phenomenon of an unexpected favourable outcome of smokers post acute myocardial infarction. There are conflicting evidences from the literature so far. We investigate for the existence of this phenomenon in our post acute myocardial infarction patients.
  
  
  METHODS
  We analysed 12,442 active smokers and 10,666 never-smokers diagnosed with STEMI and NSTEMI from the Malaysian National Cardiovascular Database-Acute Coronary Syndrome (NCVD-ACS) year 2006-2013 from 18 hospitals across Malaysia. Comparisons in the baseline characteristics, clinical presentation, in-hospital treatment and short term clinical outcome were made between the two groups. To compare the clinical outcome, an extensive multivariate adjustment was made to estimate the allcause mortality risk ratios for both groups.
  
  
  RESULTS
  The active smokers were younger (smokers 53.7 years vs non-smokers 62.3 years P < 0.001) and had lower cardiovascular risk burden and other co-morbidities. STEMI is more common in smokers and intravenous thrombolysis was the main reperfusion therapy in both groups. Smokers had a higher rate of in-hsopital coronary revascularisation in NSTEMI group (21.6 % smokers vs 16.7 % non-smokers P < 0.001) but similar to non-smokers in the STEMI group. Multivariate adjusted mortality risk ratios showed significantly lower mortality risks of smokers at both in-hospital (RR 0.510 [95 % CI 0.442-0.613]) and 30-day post discharge (RR 0.534 [95 % CI 0.437-0.621]).
  
  
  CONCLUSIONS
  Smoking seems to be associated with a favourable outcome post myocardial infarction. The phenomenon of 'smoker's paradox' is in fact a reality in our patients population. The definitive explanation for this unexpected protective effect of smoking remains unclear.
authors.affiliation: Cardiology Unit, Department of Medicine, University Malaya Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: Padmaa
authors.initials: P
authors.lastname: Venkatason
authors.affiliation: Cardiology Unit, Department of Medicine, University Malaya Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: Norsabihin Mohd
authors.initials: NM
authors.lastname: Salleh
authors.affiliation: Center for Foundation Studies in Science, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zubairi
authors.affiliation: Cardiology Unit, Department of Medicine, University Malaya Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: Imran
authors.initials: I
authors.lastname: Hafidz
authors.affiliation: Cardiology Unit, Department of Medicine, University Malaya Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: Wan Azman Wan
authors.initials: WA
authors.lastname: Ahmad
authors.affiliation: National Heart Association of Malaysia, Jalan Tun Razak, Kuala Lumpur, Malaysia.
authors.forename: Sim Kui
authors.initials: SK
authors.lastname: Han
authors.affiliation: Cardiology Unit, Department of Medicine, University Malaya Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: Ahmad Syadi Mahmood
authors.initials: AS
authors.lastname: Zuhdi