Behavioural aspects of smoking (both passive and active) and alcohol consumption on the risk of myocardial infarction

Objectives: To investigate the effect of alcohol consumption and of passive and active smoking on the risk of myocardial infarction (MI).

Methods: Data on 429 cases with MI and 434 controls was obtained through an interviewer-led questionnaire as part of the Maltese Acute Myocardial Infarction (MAMI) Study. Regular alcohol drinkers were defined as subjects having at least one drink per week for one year and binge drinkers as having six or more drinks on one occasion this last year. Current smokers were excluded from the analysis of passive smoking. Odds ratios (AdjOR) were adjusted for age, gender, smoking/drinking alcohol, hypertension, diabetes, hypercholesterolaemia and BMI.

Results: Regular alcohol drinkers were protected against MI [AdjOR 0.6 (95%CI 0.4-0.8)]. The risk of MI associated with binge drinking varies with the frequency, reaching an AdjOR of 5.8 (95%CI 1.2-27.1) in daily binge drinkers. The AdjOR for current smokers was 3.1 (95%CI 2.0-4.9) and for ex-smokers 1.6 (95%CI 1.1-2.4). Passive smoking also increased the risk of MI [AdjOR 3.0 (95%CI 1.7-5.4)]. Passive smoke exposure in a home setting had a greater deleterious effect [AdjOR 2.8 (95%CI 1.6-4.7)] than exposure in a public setting [AdjOR 1.4 (95%CI 0.9-2.2)]. While periods of 1 hour or longer of passive smoke exposure were found to be deleterious in both the investigated settings, exposure for less than 1 hour was only a risk factor in a home setting.

Conclusion: The effect of alcohol consumption on the risk for MI varies from protective to extremely deleterious depending on the frequency of drinking. Daily binge drinking is associated with a high risk of MI. Smoking, even passive smoking, is a risk factor of MI. The effect of passive smoking on the risk of MI is greater in a home than in a public setting.