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Open Access Highly Accessed Research article

The effect of tobacco smoking and treatment strategy on the one-year mortality of patients with acute non-ST-segment elevation myocardial infarction

Erlend Aune1*, Knut Endresen2, Jo Roislien34, Joran Hjelmesaeth4 and Jan Erik Otterstad1

Author Affiliations

1 Department of Cardiology, Vestfold Hospital Trust, Toensberg, Norway

2 Department of Cardiology, Rikshospitalet University Hospital, Oslo, Norway

3 Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway

4 Morbid Obesity Center, Vestfold Hospital Trust, Toensberg, Norway

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BMC Cardiovascular Disorders 2010, 10:59  doi:10.1186/1471-2261-10-59

Published: 15 December 2010

Abstract

Background

The aim of the present study was to investigate whether a previously shown survival benefit resulting from routine early invasive management of unselected patients with acute non-ST-segment elevation myocardial infarction (NSTEMI) may differ according to smoking status and age.

Methods

Post-hoc analysis of a prospective observational cohort study of consecutive patients admitted for NSTEMI in 2003 (conservative strategy cohort [CS]; n = 185) and 2006 (invasive strategy cohort [IS]; n = 200). A strategy for transfer to a high-volume invasive center and routine early invasive management was implemented in 2005. Patients were subdivided into current smokers and non-smokers (including ex-smokers) on admission.

Results

The one-year mortality rate of smokers was reduced from 37% in the CS to 6% in the IS (p < 0.001), and from 30% to 23% for non-smokers (p = 0.18). Non-smokers were considerably older than smokers (median age 80 vs. 63 years, p < 0.001). The percentage of smokers who underwent revascularization (angioplasty or coronary artery bypass grafting) within 7 days increased from 9% in the CS to 53% in the IS (p < 0.001). The corresponding numbers for non-smokers were 5% and 27% (p < 0.001). There was no interaction between strategy and age (p = 0.25), as opposed to a significant interaction between strategy and smoking status (p = 0.024). Current smoking was an independent predictor of one-year mortality (hazard ratio 2.61, 95% confidence interval 1.43-4.79, p = 0.002).

Conclusions

The treatment effect of an early invasive strategy in unselected patients with NSTEMI was more pronounced among smokers than non-smokers. The benefit for smokers was not entirely explained by differences in baseline confounders, such as their younger age.