Long-term findings from the Copenhagen City Heart Study, published in Sci Rep by Isozaki et al. in 2026, indicate that sudden cardiac death (SCD) risk increases substantially with cumulative smoking exposure and declines only gradually after smoking cessation. Researchers analyzed 10,038 participants followed for a median of 28.6 years, recording 890 SCD events across 188,870 person-years of follow-up. Compared with never smokers, current smokers face a significantly greater risk of SCD, and former smokers also maintain an elevated hazard over prolonged periods.
Evaluating Cumulative Smoking Exposure and SCD Risk
The Copenhagen City Heart Study assessed smoking exposure using status, cumulative pack-years, and time since quitting. At the 20-year mark, cumulative SCD incidence reached 2.4% among never smokers, 3.2% among former smokers, and 3.8% among current smokers. Furthermore, SCD consistently represented a substantial proportion of cardiac mortality across all evaluated smoking categories, according to the findings.
A clear dose-response relationship emerged when researchers examined cumulative pack-years. Risk increased progressively across longer exposure lengths. Independent analyses showed that both smoking intensity and smoking duration contributed directly to the hazard. Each 10-cigarette-per-day increase in intensity correlated with higher SCD risk, while each 10-year increase in duration drove up the hazard further. Those results diverge from data collected by the Nurses’ Health Study, which observed 101,018 women throughout a 30-year period and noted 351 SCD occurrences, determining that active smokers faced a 2.46-fold (95% CI, 1.81–3.33) higher probability of SCD once coronary risk elements were accounted for.
Pro Tip: Healthcare providers evaluating cardiovascular risk should record detailed pack-year histories rather than binary smoking statuses alone, as duration and intensity independently compound sudden cardiac death hazards.
The Slow Timeline of Smoking Cessation Benefits
Stopping smoking eventually lowers SCD risk, but the recovery process takes decades. Individuals who quit smoking within the preceding 0 to 6 years experienced greater than twice the likelihood of sudden cardiac death relative to lifelong non-smokers, according to information from the Copenhagen investigation. Risk remained elevated even among individuals who maintained abstinence for 15 to 26 years. Only participants with the longest duration of abstinence—spanning 26 to 67 years—showed a risk approaching that of never smokers.
The data imply that a high amount of total tobacco consumption ties closely to the threat of sudden cardiac death, whereas quitting provides substantial yet extended hazard mitigation. The study’s authors deduced that keeping people from starting smoking alongside encouraging cessation early on could serve as vital tactics to cut down the long-term prevalence of sudden cardiac death.
Did You Know? Within the Copenhagen City Heart Study, the hazard level only drew near to that of individuals who never smoked among subjects maintaining the most extended smoke-free periods of 26 to 67 years.
Frequently Asked Questions
Does sudden cardiac death risk disappear immediately after quitting smoking?
No. Research shows that former smokers remain at an elevated risk of sudden cardiac death for many years. Risk declines gradually, and only decades of abstinence bring the hazard down to the level of a never smoker.
How do smoking intensity and duration affect heart risk?
Both factors independently increase the likelihood of sudden cardiac death. Every rise of 10 cigarettes smoked daily in smoking level linked to elevated sudden cardiac death danger, whereas every 10-year extension in smoking length likewise tied to heightened vulnerability.
What did the Copenhagen City Heart Study measure?
Researchers tracked 10,038 participants over a median of 28.6 years, analyzing smoking status, cumulative pack-years, and time since smoking cessation against 890 documented sudden cardiac death events.
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