Smoking after acute myocardial infarction. A good thing?

Case fatality after an acute cardiac event: the effect of smoking and alcohol consumption

The objective of this study was to use a population-based register of acute cardiac events to investigate the association between survival after an acute event and history of smoking and alcohol consumption. The population was all residents of the Lower Hunter Region of Australia aged 25 to 69 years who suffered myocardial infarction or sudden cardiac death between 1986 and 1994. Among 10,170 events, 2504 resulted in death within 28 days. After adjusting for sex, age and medical history, current smokers had a similar risk of dying after an acute cardiac event to never-smokers [odds ratio (OR)=1.10, 95% confidence interval (CI) 0.94-1.29]. People who consumed more than 8 alcoholic drinks per day on more than 2 days per week (OR=1.93, 95% CI 1.39-2.69) and former moderate to heavy drinkers (OR=4.59, 95% CI 3.65-5.76) were more likely to die than people who were nondrinkers. The results of this large community study, suggesting no effect of smoking on case fatality and an increased risk of death after an acute cardiac event for heavy drinkers and former moderate to heavy drinkers, highlight the importance of a population view of case fatality. These results can also shed some light on reasons for the paradoxical results from clinical trials.

Smoking and prognosis after acute myocardial infarction in the thrombolytic era (Israeli Thrombolytic National Survey)

OBJECTIVES

This study sought to compare the relation between smoking and the 30-day and 6-month outcome after acute myocardial infarction in an Israeli nationwide survey.

BACKGROUND

Studies before and during the thrombolytic era reported similar or lower early mortality after acute myocardial infarction in smokers than in nonsmokers. This finding is intriguing and may be misleading because numerous epidemiologic studies have clearly shown that smoking is an independent risk factor for atherosclerosis, myocardial infarction and death.

METHODS

The study cohort comprised 999 consecutive patients with an acute myocardial infarction from a prospective nationwide survey conducted during January and February 1994 in all coronary care units operating in Israel. The prognosis of 367 patients (37%) who were smokers (current smokers and those who smoked up to 1 month before admission) was compared with that of 632 nonsmokers (past smokers or those who never smoked).

RESULTS

Smokers were on average 10 years younger and were more frequently men and patients with a family history of coronary heart disease and inferior infarction and less frequently patients with a previous infarction or a history of angina, hypertension and diabetes than nonsmokers. Smokers also had a lower incidence of congestive heart failure on admission or during the hospital period. Thrombolytic therapy (49% vs. 40%, p < 0.01) and aspirin (89% vs. 80%, p < 0.001) were administered more frequently in smokers than nonsmokers. The crude 30-day (6.0% vs. 15.7%) and cumulative 6-month (7.9% vs. 21.5%) mortality rates were significantly lower (p < 0.0001 for both) in smokers than nonsmokers, respectively. However, after adjustment for age, baseline characteristics, thrombolytic therapy and invasive coronary procedures, the lower 30-day (odds ratio [OR] 0.75, 95% confidence interval [CI] 0.43 to 1.29, p = 0.30) and 6-month (hazard ratio 0.84, 95% CI 0.54 to 1.30, p = 0.42) mortality rates in smokers and nonsmokers were not significantly different. The model had a power of 0.80 for OR 0.50, with alpha 0.1.

CONCLUSIONS

In our nationwide survey, the seemingly better prognosis of smokers early after acute myocardial infarction was no longer evident after adjustment for baseline and clinical variables and may be explained by their younger age and a more favorable risk profile. Smokers develop acute myocardial infarction a decade earlier than nonsmokers. Efforts to lower the prevalence of smoking should continue.