SMOKING PROMOTES

• lowered HDL-cholesterol (High Density Lipoprotein) levels, facilitating the development of atherosclerotic lesions ;

• increased thrombotic risk due to increased platelet aggregation, fibrinogen levels and blood viscosity (increase in figurative blood elements);

• altered endothelium-dependent arterial vasomotricity, which explains the frequency of coronary spasm;

• a high concentration of circulating CO, impairing the normal transport of oxygen by hemoglobin.

Nicotine has no specific role in the cardiovascular complications of smoking. It is essentially responsible for addiction. Its hemodynamic effects are limited to minor changes in heart rate and systolic blood pressure through adrenergic stimulation. These effects are present in nicotinemia levels induced by burning a cigarette, but are totally absent in levels obtained with nicotine substitutes, whatever the dose and route of administration.

In the Interheart study, smoking was the second most important risk factor for MI, just behind dyslipidemia. This study confirms that :

• the risk of myocardial infarction is proportional to consumption, but there is no threshold below which smoking is risk-free. The mechanisms involved are sensitive to very low levels of exposure, with a non-linear dose-effect;

• the risk is the same whatever the type of smoking (filtered or unfiltered cigarettes, pipe, cigar, hookah, chewing tobacco, etc.);

• the younger the subject, the greater the contribution of smoking to the onset of MI. It is the essential and often isolated factor in acute coronary events in young subjects;

• the risk of MI also concerns passive smoking, with a 24% increase in risk for exposure of 1 to 7 hours/week, and a 62% increase for exposure of more than 22 hours/week.

In addition to coronary complications, smoking plays a major role in the onset and evolution of obliterative arteriopathy of the lower limbs: 90% of patients with this atherosclerotic location are smokers. The risk of developing an abdominal aortic aneurysm is significantly increased in smokers.

Finally, epidemiological studies show a correlation between tobacco consumption and the risk of stroke in both men and women.

Source: French Society of Cardiology