Quitting smoking after first CV event strongly lowers risk of recurrent event and mortality
Smoking cessation and risk of recurrent cardiovascular events and mortality after a first manifestation of arterial disease
Introduction and methods
According to EUROASPIRE, the proportion of smokers in European patients with coronary artery disease (CAD) has only decreased slightly over the past 15 years, from 20% to 16% in 2013 .
The effect of smoking cessation on reduction of CV risk appears to be greater than pharmaceutical treatment of major risk factors such as cholesterol and blood pressure or the use of antiplatelet therapy .
Two studies have shown that cessation of smoking, even at the age of 60, was related to improved survival, and associated with an average gain of 3 years compared to patients who continued smoking. It should be noted, however, that presence of CV disease was not taken into account in these studies [3,4]. Moreover, in patients of 65 years and older, who were admitted for acute myocardial infarction between 1994 and 1996, cessation of smoking after the event, until the age of 70 years, was found to improve survival with 1 year .
This study aimed to describe the prevalence and characteristics of patients after a recent first manifestation of arterial disease according to smoking status, as well as to quantify the relation between smoking status and risk of recurrent CV events and mortality. The study was performed in a contemporary cohort (Second Manifestations of ARTerial disease (SMART) study) of patients with a variety of arterial disease manifestations, taking age at onset of a first CV event and type of vascular disease into account. Patients are enrolled in the SMART cohort when they have reached a stable situation in their disease. Smoking behavior was categorized as follows: never smoked, former smoker (stopped prior to the vascular event), quit after vascular event (in same year or in year after event) or continued after vascular event. One pack-year was defined as smoking 20 cigarettes a day for 1 year.
- At the time of the first event, 22% had never smoked, 46% were former smokers and 32% smoked. About a third of smokers (12% of whole cohort) quit smoking and two-thirds (21% of total) continued to smoke.
- Over the course of the study, the proportion of never smokers increased, from 15% to 28%, and persistent smokers declined (37% to 11%).
- During a median follow-up of 7.4 years (IQR: 3.7-10.8), 17% (794) of patients died, 47% (377) of whom due to a vascular cause. MACE occurred in 15% (692) of patients and MACE including vascular interventions occurred in 35% (1640) patients.
- When comparing those who continued to smoke and those who quit smoking after the event, the quitters had a lower risk of recurrent MACE (HR: 0.64, 95%CI: 0.48-0.86), and of recurrent MACE including vascular interventions (HR: 0.79, 95%CI: 0.67-0.95), and of all-cause mortality (HR: 0.62, 0.48-0.80).
- Those who never smoked had the lowest risks as compared to those who continued to smoke, with HR: 0.56 for recurrent MACE, HR: 0.65 for recurrent MACE plus vascular interventions and HR: 0.42 for all-cause mortality.
- Irrespective of age, patients who quit after a first CV event lived on average 5 years longer than patients who continued to smoke. At the age of 60 years, those who quit smoking after an event had a recurrent event on average 10 years later than those who continued.
- Linear relationships were seen between pack-years of smoking (≤5 pack-years vs >5: HR: 0.73, 95%CI: 0.61-0.88), years since smoking cessation (negative relation) or age at smoking cessation (positive) and risk of recurrent MACE.
This study shows that, irrespective of age, cessation of smoking after a first CV event is related to a much lower risk of recurrent vascular events and mortality, compared to patients who did not quit after the event. Quitters lived about five years longer than patients who continued to smoke, and recurrent events were delayed by about 10 years.