• Researchers report that people with coronary artery disease can reduce their risk of heart attack by 44% by quitting smoking.
• The risk for people with this condition increases by 8% for every year they continue to smoke.
• People who only reduce the amount they smoke don’t lower their risk when compared to people who continue to smoke, researchers say.
• Experts advise people both with and without coronary artery disease to stop smoking as soon as possible.

Quitting smoking can significantly reduce the risk of a heart attack for those diagnosed with coronary artery disease, according to a new study.

However, researchers report that simply cutting back on smoking doesn’t appear to do much to lower the risk.

In addition, people who have never smoked still have a lower overall risk of a major cardiovascular event than a person who has quit smoking, even if that person has stopped tobacco use for years.

These findings were presented on August 29 in London at the ESC Congress 2024, the annual meeting of the European
Society of Cardiology.

Although the research has yet to be published in a peer-reviewed journal, experts say it sends an important and strong message.

“This analysis reinforces what has been known from previous smaller studies in years past: there is no safe level of cigarette smoking,” said Richard Wright, MD, a cardiologist at Providence Saint John’s Health Center in Santa Monica, California.

“The noxious components of smoke immediately lead to a chain of noxious events, and whether one
smokes a quarter-pack or two packs of cigarettes is irrelevant with regards to the increase in cardiac
risk. This enhanced risk also extends to those exposed to second-hand smoke,” Wright told Healthline.

Smoking and heart attack risk

In their study, researchers assessed data from the international CLARIFY registry, a databank that has
been used in past cardiovascular research.

The researchers examined 32,378 people with coronary artery disease. The participants were studied at an average of about six years after their disease diagnosis.

Among the participants at the start of the study:

• 41% had never smoked
• 46% were former smokers
• 12% were current smokers

Among the former smokers who were smoking at the time of their coronary artery disease diagnosis:

• 73% had discontinued smoking within a year of their diagnosis
• 27% quit in subsequent years

Researchers reported that people who quit smoking after their diagnosis saw an overall reduction of 44% in the risk of a major adverse cardiovascular event, regardless of when they stopped tobacco use.

The researchers noted, however, that the risk of a heart attack or other cardiovascular event increased by 8% for each additional year of active smoking.

They pointed out that study participants who reduced the amount they smoked didn’t have a significantly lower risk than participants who continued to use tobacco.

They added that the former smokers “never achieved the cardiovascular risk level of patients who never smoked, even after years of smoking cessation.”

“I like to tell my patients that it is never too soon or too late to stop smoking, though the sooner a patient stops, the better to lower cardiovascular risk,” study author Jules Mesnier, MD, a cardiologist at the Hospital Bichat-Claude Bernard in Paris, in a statement.

“And it is not enough to reduce smoking. Short, clear-cut messages are needed for smokers at every medical intervention highlighting the need to quit,” Mesnier continued.

How smoking affects cardiovascular health

Robert Page, PharmD, professor of clinical pharmacy and physical medicine at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences and member of the Drug, Alcohol and Tobacco Use Committee of the American Heart Association’s Council on Lifestyle and Cardiometabolic Health, said the information contained in the new study is powerful. Page was not involved in the study.

“What is quite compelling is that even after quitting smoking, patients did not return to their prior baseline cardiovascular risk status before they began smoking,” he told Healthline.

“While this study was based on registry data, I want to point out that this is only an association and not direct causation; however, with the amount of robust data on the [cardiovascular] effects of smoking and consistent biological plausibility, these data are quite powerful, especially when educating patients,” Page continued.

Dr. Cheng-Han Chen, an interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in California, agreed with the strong message of the research. Chen wasn’t involved in the study.

“This study found that quitting smoking, and not just cutting down on smoking, can reduce the risk of a major cardiovascular event by half. This is consistent with our current understanding and recommendations to completely quit smoking rather than cutting down, in order to gain the most health benefits. However, cutting down on smoking can potentially be useful if it puts someone on the path to eventually quit,” Chen told Healthline.

“Our advice is very clear to people with coronary artery disease who smoke: quitting smoking is essential to minimize the risk of a future cardiovascular event, and can potentially be life-saving,” he added.

Jayne Morgan, MD, a cardiologist and vice president of medical affairs at Hello Heart, who is not involved in the study but is attending the ESC conference, said smoking can produce a number of health issues for people with coronary artery disease.

“Smoking damages the endothelial lining of the coronary arteries in an irreversible fashion. This sets a
person up for the development of atherosclerosis. which can then lead to a heart attack and heart
failure,” Morgan told Healthline.

“Additionally, smoking further accelerates the development of atherosclerosis where it is already present, further narrowing the coronary arteries and reducing blood flow and critical oxygen supply to the heart,” she said.

“Moreover, smoking increases levels of certain blood clotting factors further complicating the picture and putting the patient at risk of a cardiovascular event,” Morgan added.

“And then when you just think about nicotine itself, which causes vasoconstriction or tightening of the coronary arteries further reducing blood flow that may already be reduced by atherosclerosis. Then we must consider that inflammatory response of the body to smoking, including the coronary arteries,” Morgan continued.

Health dangers of smoking

Page said the dangers of smoking extend far beyond people with coronary artery disease.

“Active smoking and secondhand smoke exposure determine over 30% of coronary heart disease deaths,” he explained.

“While the exact mechanisms of cardiovascular damages are not well known, the detrimental effect of smoking on endothelial function has long been recognized. Smoking elicits oxidative processes, negatively affects platelet function, fibrinolysis, inflammation and vasomotor function. All of these accelerate early onset ASCVD disease. Thus, I tell patients, ‘Why even start smoking?,’ he added.

Page said he tries to hammer home this message in particular to young adults and teens.

“I have found that teens and young adults believe they are invincible and that ‘this won’t happen to me’ or ‘I just smoke socially.’ These are urban myths and completely false assumptions based on these data,” he said.

Morgan said the health dangers from tobacco use can be particularly acute for women.

“If you are a female, the coronary arteries are generally smaller and these effects of smoking (cardiac events, i.e. heart attacks) may therefore become evident sooner with earlier cardiac events,” she said.

“If you are in perimenopause or menopause (generally 35 to 60 years of age), you may be at particularly high risk. Further, if you have other risk factors that put your body at risk of chronic inflammation, such as obesity and diabetes — even more of a reason to quit smoking,” Morgan noted.

Strategies to quit smoking

Mesnier said measures to promote smoking cessation should include advice, counseling, behavioral interventions, and pharmacological therapy when necessary. Talking with a healthcare professional can be an important step to quit smoking.

Page noted that smokers, as well as medical professionals, must acknowledge how difficult it can be to quit this unhealthy habit.

“It is hard to believe that after more than a half century of research, people continue to smoke, which speaks to the great addiction potential of cigarettes,” he said. “It is important to note that patients have to want to quit, and having them tell you directly a specific quit date is essential.”

Morgan has straightforward advice for people who don’t smoke: “Don’t start. If you have started, there is no better time than now to quit,” she said.

Wright also has some direct advice: “The message is simple. Don’t take up smoking, especially if you are known to have coronary disease,” he said.

“If you do smoke, quit. Now. You will benefit by next month. In about a decade, that excess risk will evaporate — but only if abstention from cigarette smoke is complete,” Wright concluded.

Takeaway

In a new study, researchers say people with coronary artery disease who stop smoking can lower their risk of heart attack or other major cardiovascular event by 44%, no matter when they quit tobacco use.

However, researchers noted that the risk increases by 8% for every year a person with coronary artery disease continues to stop. They added that people with this condition who reduce the amount they smoke don’t appear to have a lower risk than people who continue to smoke.

Experts say the sooner anyone quits smoking the healthier they will be.