Even light smoking (2–5 cigarettes/day) linked to 50% higher heart failure risk, 60% higher all-cause mortality, with elevated risk persisting for decades after cessation (sciencedaily.com)

• Meta-analysis of 22 studies (n>300,000) found 2–5 cigarettes/day increases heart failure risk 50% and all-cause mortality 60%.
• Greatest risk reduction occurs within first 10 years of quitting, but elevated risk persists up to 30 years post-cessation.
• Complete cessation at younger age is far more protective than reducing cigarette consumption.

"A large meta-analysis of 22 longitudinal studies covering over 300,000 adults found that smoking just 2–5 cigarettes per day increases heart failure risk by 50% and all-cause mortality by 60% compared to never-smokers. The greatest risk reduction occurs within the first 10 years of quitting, but former smokers remain at elevated risk for up to 30 years. The study highlights that complete cessation, especially at younger ages, is far more protective than simply reducing cigarette consumption."