Smoking is not a protective factor for patients with acute myocardial infarction: the viewpoint of the GISSI-2 Study

BACKGROUND: A protective role of smoking in terms of mortality after acute myocardial infarction treated with thrombolytic agents was recently suggested, and this was attributed to the increased chance that smokers will achieve early complete perfusion after thrombolysis. The purpose of the present analysis of the GISSI-2 database was to evaluate the effect of smoking on in-hospital mortality, reinfarction and stroke rates. METHODS AND RESULTS: This analysis concerns 2611 (26.9%) nonsmokers, 1932 (19.9%) ex-smokers and 5151 (53.0%) active smokers with a first confirmed MI, treated with thrombolytic agents. The relationship between smoking habits and outcome was evaluated by unadjusted and adjusted analysis. Reinfarction and stroke rates were significantly lower in smokers (1.5 and 0.8% respectively) than in ex-smokers (2.5 and 1.1%) or nonsmokers (2.5% and 1.2%). In-hospital mortality significantly increased from 4.7% in smokers, to 7.6% in ex-smokers and 13.8% in nonsmokers. These differences may be due to the different characteristics of the three groups; in particular, smokers were younger than nonsmokers. After adjusted analysis, smoking was not confirmed to be a protective factor for reinfarction, stroke and mortality: OR 1.35 (95% Cl 0.91-2.02), 0.79 (95% Cl 0.58-1.06) and 0.80 (95% Cl 0.60-1.07) respectively. CONCLUSIONS: Active smokers presented a lower incidence of reinfarction, stroke and in-hospital mortality rates, but after adjustment for other clinical-epidemiological variables, the apparent protective role of smoking was not confirmed.