Smoking and cardiovascular risk

When people think of the harms of smoking, they think first of lung cancer. Yet the heart and arteries are on the front line. Among all the cardiovascular risk factors you can act on, tobacco occupies a special place: it's the one whose cessation produces the fastest, and one of the largest, effects.

A considerable toll

In France, of the 68,000 deaths Santé publique France attributed to tobacco in 2023, about 14,000 are due to cardiovascular disease. One cardiovascular death in ten is linked to tobacco. In the United States, where tobacco causes about 480,000 deaths a year according to the CDC, heart and vascular disease account for nearly a third of them. Worldwide, the World Health Organization (WHO) attributes more than 7 million deaths a year to tobacco, including 1.6 million among non-smokers exposed to other people's smoke.

The international INTERHEART study, conducted in 52 countries and published in 2004 in The Lancet, showed that smokers had an almost three-fold higher risk of heart attack than people who had never smoked. Tobacco alone accounted for more than a third of heart attacks in the population studied.

Tobacco weighs particularly heavily on younger people. Before age 50, the large majority of heart attack victims are smokers, according to the French Federation of Cardiology. In women, combining smoking with estrogen-containing contraception strongly increases the risk of a cardiovascular event, especially after age 35.

A number that speaks for itself

According to the French Federation of Cardiology, quitting smoking reduces the risk of heart attack by at least 50%. For comparison, treating high blood pressure reduces that same risk by about 20%, and treating high cholesterol by about 29%. Quitting smoking, on its own, therefore outweighs the combined effect of managing two other major cardiovascular risk factors. These treatments remain useful, of course: they add to quitting smoking, they don't replace it.

How tobacco damages the heart and blood vessels

Tobacco acts through several mechanisms at once.

• Inhaled carbon monoxide takes the place of oxygen on red blood cells. The blood carries less oxygen, and the heart has to work harder to deliver as much to the organs.
• Nicotine stimulates the release of adrenaline. With every cigarette, heart rate and blood pressure rise, and arteries constrict.
• Smoke damages the inner lining of arteries, called the endothelium. It causes inflammation and oxidative stress that speed up the buildup of fatty plaques: atherosclerosis.
• Blood becomes thicker and clots more easily. Platelets clump together more, promoting clot formation (thrombosis). It's a clot forming on a plaque that triggers most heart attacks and a large share of strokes.
• Tobacco can trigger a spasm of the heart's arteries, that is, a sudden narrowing, sometimes even in young people whose arteries are otherwise barely damaged.
• It alters blood fats: it lowers “good” cholesterol (HDL), which protects arteries.

Beyond heart attack

The consequences aren't limited to the heart.

Stroke. Tobacco roughly doubles stroke risk, by promoting both atherosclerosis in the neck arteries and clot formation.

Peripheral artery disease. Disease of the arteries in the legs, which shows up as pain while walking, is the cardiovascular disease most closely linked to tobacco: the vast majority of people affected smoke or have smoked. Quitting is the first treatment.

Abdominal aortic aneurysm. This bulging of the body's main artery, which can rupture, mainly affects men who smoke or used to smoke. This is why ultrasound screening is offered to them from age 65.

Erectile dysfunction. It's often the first sign of arterial damage, and smoking is a frequent cause of it.

There's no small amount of smoking without risk

It's often believed that smoking a little divides the risk by the same amount. That isn't true for the heart. An analysis of 141 studies, published in 2018 in the BMJ (Hackshaw et al.), showed that smoking just one cigarette a day already carried about half the excess coronary risk associated with twenty cigarettes a day in men (46%), and about a third in women (31%). For stroke, the proportions were 41% and 34%.

The reason is that some effects, such as platelet activation and arterial spasm, appear from very low doses. Cutting back is a useful first step toward quitting, but only complete cessation truly protects the heart.

Secondhand smoke follows the same logic. Living or working in other people's smoke increases the risk of coronary heart disease by about 25 to 30% in non-smokers, according to reports from the U.S. Surgeon General. In several countries, bans on smoking in public places were followed by a rapid drop in hospitalizations for heart attack.

E-cigarettes, finally, eliminate combustion and carbon monoxide. Their long-term cardiovascular effects aren't yet known. They can help with quitting, provided you don't keep smoking alongside them.

A benefit that begins the moment you quit

Contrary to a common belief, the cardiovascular benefits of quitting don't take years to appear. Within the first twenty minutes, heart rate and blood pressure come back down. Within twenty-four to forty-eight hours, carbon monoxide and nicotine have cleared from the body, and the risk of arterial spasm and clotting is already markedly lower. After one year, the excess risk of coronary heart disease is cut in half. After about fifteen years, it matches that of someone who never smoked.

This benefit also holds once disease is already present. A review published in 2003 in JAMA (Critchley and Capewell), pooling twenty studies, showed that quitting smoking after a heart attack, or in someone with coronary heart disease, reduced mortality by about 36%. No medication taken alone does better.

A factor that multiplies the risk from other factors

Tobacco doesn't act alone. Combined with high blood pressure, diabetes, or high cholesterol, it multiplies overall cardiovascular risk rather than simply adding to it. This is why, in the overall cardiovascular risk calculation (SCORE2), smoking status is taken into account alongside blood pressure and cholesterol. A smoker whose profile is otherwise favorable can end up at a markedly higher risk level than a comparable non-smoker. The Do I have high blood pressure? and Am I at risk of diabetes? tools can help you take stock of these other factors.

What to remember

If only one modifiable cardiovascular risk factor had to come first, it would be tobacco. Not because the others matter less, but because the effect of quitting is both fast and large, at any age and even after a cardiac event. Assessing your level of dependence, as the Fagerström test lets you do, is a concrete first step before choosing a suitable quitting strategy with a healthcare professional. In France, Tabac Info Service (39 89) can support this process free of charge; in the United States, 1-800-QUIT-NOW offers the same kind of free support.

To assess your own level of dependence, take the “Am I dependent on tobacco?” test.