In the CLARIFY registry of 32,378 outpatients with stable coronary artery disease followed for five years, active smokers who quit had a 44% lower risk of cardiovascular death or myocardial infarction (aHR 0.56, 95% CI 0.42-0.76), regardless of when they quit. Reducing cigarettes without stopping showed no benefit. Former smokers never reached the risk level of lifelong never-smokers, however long they stayed abstinent, and each extra year of smoking after diagnosis added risk. Only about 12% of smokers quit annually.
The cessation benefit is consistent with decades of secondary-prevention data, so the headline is confirmatory. The more useful findings are the null result for cutting down and the persistent residual risk in ex-smokers. Reduction is a common compromise between patient and clinician, yet earlier work in general populations also suggests that halving consumption recovers little of the cardiovascular hazard, since even a few cigarettes a day drive endothelial dysfunction and thrombosis. The residual risk likely reflects lasting vascular damage and shared confounders. Limitations matter: this is observational, so healthy-quitter bias and reverse causation are possible, as patients who feel unwell may quit or smoke less. Smoking status was self-reported, with no cotinine verification, and the active-smoker subgroup is small, giving wide confidence intervals. Still, the message for patients is clear: quitting remains worthwhile years after a coronary diagnosis, and partial reduction should not be treated as an adequate endpoint. Clinicians should push for complete cessation with pharmacotherapy and counselling rather than accept a lower daily count.