Quitting smoking associated with reduced risk of adverse outcomes after PCI

Introduction and methods

Background

Although the impact of smoking on the clinical outcomes of patients undergoing coronary revascularization has been investigated [1-4], large-scale, population-based studies on this subject are missing. And in particular, there have been no studies in the contemporary drug-eluting stent era. Moreover, the impact of smoking cessation after PCI remains to be elucidated.

Aim of the study

The study aim was to investigate the effects of smoking status before and after PCI on long-term clinical outcomes.

Methods

The authors extracted data of 74,471 patients undergoing PCI in the Republic of Korea from 2009 through 2016 from a nationwide database from the Korean National Health Insurance System (NHIS). All Koreans enrolled in the NHIS are encouraged to undergo regular health check-ups at least every 2 years. Information on the status and amount of smoking was collected through self-reported questionnaires. Participants were classified depending on their smoking status at the first health check-up within 1 year after PCI: non-smoker (n=33,783), ex-smoker (n=28,713), or current smoker (n=11,975). Median follow-up duration was 4.0 years.

To assess the effects of smoking cessation after PCI, data of 31,887 patients with both pre- and post-PCI health check-up data (median time between the 2 health check-ups: 628 days; IQR: 390–740) were analyzed, excluding patients who stopped smoking before the index PCI and those who newly started smoking after the index PCI. Of these 31,887 patients, 17,602 were still non-smokers at the first health check-up after PCI, 7546 had stopped smoking after PCI, and 6739 smokers had kept smoking.

Outcomes

The primary endpoint was major adverse CV and cerebrovascular events (MACCE), a composite outcome of all-cause mortality, MI, coronary revascularization, or stroke. Secondary endpoints were the individual components of the primary endpoint.

Main results

Effects of smoking status on clinical outcomes

• Multivariable-adjusted Cox proportional hazards analysis showed that current smokers had a higher rate of MACCE compared with non-smokers (adjusted HR (aHR): 1.198; 95%CI: 1.137–1.263). This was mainly driven by a higher rate of all-cause mortality in current smokers compared with non-smokers (aHR: 1.606; 95%CI: 1.465–1.760).
• Ex-smokers tended to have a MACCE rate comparable with that of non-smokers (aHR: 1.036; 95%CI: 0.992–1.081).

Effects of smoking cessation after PCI on clinical outcomes

• Among patients who stopped smoking after PCI, quitters with a cumulative smoking exposure of 20–29 pack-years had an increased MACCE rate compared with persistent non-smokers (aHR: 1.206; 95%CI: 1.054–1.380), as did quitters with ≥30 pack-years (aHR: 1.227; 95%CI: 1.113–1.352). Their MACCE rates were similar to that of persistent smokers (aHR: 1.223; 95%CI: 1.126–1.328).
• Quitters with <10 pack-years tended to have a MACCE rate comparable with that of persistent non-smokers (aHR: 1.182; 95%CI: 0.971–1.438), as did quitters with 10–19 pack-years (aHR: 1.114; 95%CI: 0.963–1.290).

Subgroup analysis

• Subgroup analysis showed consistently higher MACCE rates in current smokers and ex-smokers compared with non-smokers across various subgroups, including in older versus younger patients and in patients with versus without a risk factor at the index PCI, such as hypertension, diabetes, dyslipidemia, or MI.
• Interestingly, the adverse clinical outcomes in current smokers and ex-smokers were more pronounced in those without these risk factors.

Conclusion

References

Find this article online at Eur Heart J.