Can prior cigarette smoking leave persistent endothelial dysfunction and atherosclerotic risk after quitting?

Former cigarette smoking remains clinically relevant because vascular risk falls substantially after quitting but may not return promptly to that of never-smokers, especially after higher cumulative exposure.

Clinical and imaging evidence

• In a cohort of 5.3 million people, former smokers with ≥8 pack-years retained statistically detectable excess cardiovascular risk versus never-smokers until more than 25 years after cessation. Those with lower cumulative exposure had no significant residual excess risk.
• Pooled cohort data similarly show major risk reduction compared with continued smoking, while heavier former smokers retain excess risk for years.
• Multimodality imaging meta-analysis found that former smokers have an intermediate coronary plaque burden—lower than current smokers but greater than never-smokers—supporting durable atherosclerotic consequences of prior exposure.

Endothelial and mechanistic interpretation

• Smoking impairs nitric-oxide–dependent endothelial function in an exposure-related fashion. Cessation improves flow-mediated dilation over one year, and longer abstinence is associated with better resistance-artery endothelial measures. This supports recovery, but potentially incomplete or heterogeneous recovery after substantial exposure.
• Tobacco smoke increases reactive oxygen species, which scavenge nitric oxide and promote endothelial nitric-oxide synthase (eNOS) uncoupling, including through reduced tetrahydrobiopterin. The resulting reduction in nitric oxide bioavailability impairs endothelium-dependent vasodilation.
• Oxidative and nitric-oxide abnormalities generally improve after cessation. Their role as persistent mediators in former smokers is therefore biologically credible but not directly established. Likewise, durable vascular remodeling is consistent with persistent plaque burden and risk, but has not been directly demonstrated as the causal bridge to later endothelial dysfunction or events.

Bottom line

• Prior heavy smoking can leave long-lived excess atherosclerotic risk despite cessation; persistent endothelial dysfunction and lasting oxidative/NO-related or structural vascular effects are plausible explanations, while quitting still produces substantial vascular recovery.