Quitting smoking reduces the risk of major cardiovascular events by almost half

Patients with stable coronary artery disease who quit smoking permanently after diagnosis reduced their risk of major events by 44%, according to a study presented at the European Society of Cardiology (ESC) Congress 2024. In contrast, the impact on cardiovascular risk was minimal in patients who only reduced their smoking.[1]. 

The international CLARIFY (prospective observational Longitudinal Registry of patients with stable coronary artery disease) registry evaluated the impact of smoking on cardiovascular events in patients with coronary artery disease. The registry included 32,378 cardiac patients. The occurrence of a major adverse cardiovascular event (MACE), defined as cardiovascular death or myocardial infarction during the 5-year follow-up period, was analyzed.

Simply reducing smoking has no significant impact

Patients were included in the study an average of 6.5 years after their coronary heart disease diagnosis: at inclusion, 13,366 patients (41.3 %) had never smoked, 14,973 (46.2 %) were former smokers, and 4,039 (12.5 %) were current smokers. Among former smokers who were smoking at the time of coronary heart disease diagnosis, 72.8 % quit smoking within the following year, while only 27.2 % quit smoking in the following years.

Patients who quit smoking completely after their coronary heart disease diagnosis significantly improved their cardiovascular risk regardless of when they quit, with a 44% reduction in the risk of a major cardiovascular event.

Among smokers who only reduced their smoking, the risk of MACE was not significantly changed compared with smokers who did not change their habits. The risk of MACE after a diagnosis of coronary heart disease increased by 8 % for each additional year of active smoking.

Although smokers who quit after diagnosis achieved a significant reduction in MACE risk early compared with smokers, they never reached the level of cardiovascular risk of patients who never smoked, even after years of smoking cessation.

The results of this study have not yet been published in a peer-reviewed journal, but experts believe they send an important and strong message, confirming data from several previous studies.[2].

"This analysis reinforces what has been known for years from previous, smaller studies: there is no safe level of cigarette consumption," said Dr. Richard Wright, a cardiologist at Providence Saint John's Health Center in Santa Monica, Calif.

The importance of completely quitting smoking

Smoking cessation remains the cornerstone of preventing myocardial infarction, stroke and also improving overall health, including after a cardiovascular event, at any age. Smoking is responsible for 50% of all preventable deaths among smokers, half of which are due to cardiovascular disease.

"At the time of diagnosis, we should emphasize the importance of quitting smoking and support patients in this challenge," said study author Dr. Jules Mesnier of Bichat-Claude Bernard Hospital in Paris, France.

Dr. Mesnier said measures to promote smoking cessation should include counseling, behavioral interventions and pharmacological therapy if necessary. Talking with a health professional can be an important step in quitting smoking. He adds that it is never too early or too late to quit smoking. "In every medical intervention, smokers should be given short, clear messages emphasizing the need to quit. Telling patients that they can halve the risk of a major event or subsequent death - as we have shown here - is a powerful message."

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