[Smoking cessation and risk of myocardial reinfarction in coronary patients: a nested case-control study]

Smoking cessation reduces mortality in coronary patients. The aim of this study was to estimate association measures between the risk of occurrence of fatal or non-fatal reinfarction in patients who either continue to smoke or stop after a first infarction and are treated with secondary prevention measures.

The study was a case-control (1:1) design nested in a cohort of 985 coronary patients under the age of 76 years who were not treated with invasive procedures and survived more than 6 months after the first acute myocardial infarction. Cases were all patients who suffered reinfarction (n = 137) between 1997 and 2000. A control patient was matched with each case by gender, age, hospital, interviewer, and the secondary prevention timeframe.

Patients who smoke after the first acute myocardial infarction had an Odds ratio (OR) of 2.83 (95% CI, 1.47-5.47) for a new acute myocardial infarction. Adjustment for lifestyle, drug treatment, and risk factors (family history of coronary disease, high blood pressure, hypercholesterolemia, and diabetes mellitus) did not change the OR (2.80 [95% CI, 1.35-5.80]). Patients who quit smoking had an adjusted OR of 0.90 (95% CI, 0.47-1.71) compared with non-smokers before the first acute myocardial infarction. Continued smoking had an adjusted OR of 2.90 (95% CI, 1.35-6.20) compared to quitting after the first acute myocardial infarction.

The risk of acute myocardial infarctions is three times higher in patients who continue to smoke after an acute coronary event compared with patients who quit. The risk of reinfarction in patients who stop smoking is similar to the risk of non-smokers before the first infarction.