Smoking and myocardial infarction: secondary prevention.

This prospective study examines the question 'Is it too late to stop smoking cigarettes once you have had a myocardial infarction?' One hundred and nineteen cigarette smokers (90 men, 29 women) who survived their first myocardial infarction for one month were followed for five years or until their death if earlier. The age corrected mortality rate of men who continued to smoke cigarettes was 2.2 times the age corrected mortality rate of those who stopped smoking after their infarct. The women who continued to smoke had 2.4 times the age corrected mortality of those who stopped smoking. The age and sex corrected mortality rates for the combined group of men and women show that those who stopped smoking after their infarction have 55% of the mortality of those who continued to smoke (P less than 0.05). These results suggest that smoking is not merely a 'risk factor' for myocardial infarction but is also a causal factor whose effects can be avoided by both men and women after an initial myocardial infarction.