Heavy cigarette smokers with at least a 20 pack-year smoking history can reduce their risk of cardiovascular disease (CVD) by 39% within 5 years if they quit, according to a study published today in the Journal of the American Medical Association.

But it takes at least 5 to 10 years, and perhaps up to 25 years after quitting, for CVD risk to become as low as that of a similar person who has never smoked.

"Previous studies have shown the association between quitting and reduced CVD risk," said lead author, Meredith Duncan, MA, who led the analyses for the Division of Cardiovascular Medicine at Vanderbilt University Medical Center. "But the current Atherosclerotic CVD Risk Calculator, which is routinely used in clinical practice, considers former smokers' risk to be similar to that of never smokers after 5 years of cessation, which is not consistent with these findings." Cigarette smoking is responsible for 20% of CVD deaths in the United States, the study notes.

Researchers used data from the Framingham Heart Study, a longitudinal study of men and women from Framingham, MA, which began enrollment in 1948 and now includes their children and grandchildren, as well as multiethnic cohorts.

The study used prospective data from 1954 through 2014 from 8,770 participants—3,805 from the Original cohort and 4,965 from the Offspring cohort—to determine the effect of lifetime smoking and smoking cessation on the risk of CVD, which includes myocardial infarction, stroke, CVD death, and heart failure.

"The Framingham Heart Study provides particularly robust data on lifetime smoking history," added Duncan. "Our team leveraged this unique opportunity to document what happens to CVD risk after quitting smoking relative to people who continued to smoke and to those who never smoked."

Senior author Hilary Tindle, MD, MPH, medical director of the VUMC Tobacco Treatment Service and founding director of the Vanderbilt Center for Tobacco Addiction and Lifestyle (ViTAL), urges smokers to act on these study results by putting out their cigarettes.

"The cardiovascular system begins to heal relatively quickly after quitting smoking, even for people who have smoked heavily over decades," Dr. Tindle said. "Full recovery could take years, so now is a great time to quit smoking and take other steps toward heart health."