The tobacco paradox in acute coronary syndrome. The prior cessation of smoking as a marker of a better short-term prognosis

Objective: The tobacco paradox is a phenomenon insufficiently explained by previous studies. This study analyses the prognostic role of prior or active smoking in patients with acute coronary syndrome.

Methods: We obtained data from the ARIAM registry, between 2001 and 2012. The study included 42,827 patients with acute coronary syndrome (mean age, 65±13 years; 26.4% women). The influence of smoking and that of being an ex-smoker on mortality was analysed using a multivariate analysis.

Results: The smokers were younger, were more often men, had less diabetes, hypertension and prior history of heart failure, stroke, arrhythmia and renal failure and more frequently had ST-elevation and a family history of smoking. The ex-smokers had more dyslipidaemia and history of angina, myocardial infarction, ischemic heart disease, peripheral vasculopathy and chronic bronchial disease. Smokers and ex-smokers less frequently developed cardiogenic shock (smokers 4.2%, ex-smokers 4.7% and nonsmokers 6.9%, P<.001). Hospital mortality was 7.8% for the nonsmokers, 4.9% for the ex-smokers and 3.1% for the smokers (P<.001). In the multivariate analysis, the smoker factor lost its influence in the prognosis (-0.26%, p=.52 using an inverse probability calculation; and+0.26%, P=.691 using a propensity analysis). However, the exsmoker factor showed a significant reduction in mortality in both tests (-2.4% in the inverse probability analysis, P<.001; and -1.5% in the propensity analysis, P=.005).

Conclusions: The tobacco paradox is a finding that could be explained by other prognostic factors. Smoking cessation prior to hospitalization for acute coronary syndrome is associated with a better prognosis.