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Background The smokers’ paradox was first described in clinical trials of fibrinolytic therapy for ST elevation MI (STEMI). It proposes that clinical outcomes after myocardial infarction are more favourable in smokers, potentially because of primarily thrombotic occlusion and lower atherosclerotic plaque burden compared with non-smokersPurpose We sought to evaluate the impact of baseline smoking status on 10-year mortality in patients undergoing primary PCI (PPCI) for STEMIMethods We identified all patients treated with PPCI in the Belfast Trust Heart Attack Centre during 2014 and extracted clinical information covering the subsequent 10 years from the Northern Ireland Electronic Care Record. We used Kaplan-Meier time-to-event analysis to estimate the cumulative incidence of death and a Cox proportional hazards regression model to calculate adjusted hazard ratios. Data were analysed using SPSS V.28.0Results Six-hundred and ninety-one patients (mean age 64 ± 13 years; 25.4% female) who underwent PPCI during 2014 were followed for a median of 10.5 years. Those who were smokers at the time of PPCI (n=358, 51.8%), were significantly younger (mean age 61 ± SD 13 years vs 68 ±13 years; P<0.01); there were no gender differences between groups (females 22.6% vs 28.2%, P=NS). Rates of chronic obstructive pulmonary disease were higher in smokers (15.6% vs 9.6%, P=0.022) but there was no significant difference in rates of hypertension, previous MI, diabetes mellitus or heart failure. Smokers had a significantly lower risk of death during 10-years of follow-up ( figure 1, panel a) but after adjusting for age at presentation, no difference was seen (figure 1, panel b)Conclusion During long-term follow up of patients undergoing PPCI for STEMI, smokers and non-smokers experienced similar age-adjusted rates of death. The data suggest that the smokers’ paradox is an apparent rather than a real phenomenon explained by the confounding effect of age at presentationAbstract 12 Figure 1Kaplan meier curves demonstrating 10-year survival following primary PCI for STEMI in smokers and non-smokers. a) unadjusted survival and b) after adjustment for age at presentation