For former smokers it took more than 15 years for cardiovascular disease risk to return to the level of those who never smoked, according to preliminary research to be presented in Chicago at the American Heart Association’s Scientific Sessions 2018, a premier global exchange of the latest advances in cardiovascular science for researchers and clinicians.

Cigarette smoking in the United States is on the decline, which means there are more former smokers. Studies to date suggest that the increased risk for cardiovascular disease in smokers diminishes a few years after quitting, but those studies have not been able to look as closely at smoking history, including changes in smoking habits such as variations in cigarettes smoked per day, or quitting followed by relapse to smoking.

In this study, researchers analyzed information, including lifetime smoking history, of nearly 8,700 participants of the Framingham Heart Study who were free of cardiovascular disease at the start of the study. The midpoint of follow-up among participants was 27 years, during which cardiovascular disease risk was compared among current, former and never smokers.

Researchers found:

• More than 70% of cardiovascular disease events in current or former smokers occurred among those who smoked at least 20 pack-years, which is the equivalent exposure of one pack a day for 20 years.
• Former smokers who had quit within the last 5 years reduced their cardiovascular disease risk by 38% compared to those who continued to smoke.
• It took 16 years since quitting for former smokers’ risk of cardiovascular disease to return to the level of never smokers.

“These findings underscore the benefits of quitting smoking within 5 years, which is 38% lower risk of a heart attack, stroke, or other forms of cardiovascular disease risk compared to people who continue to smoke. We also found that cardiovascular disease risk remains elevated for up to 16 years for former smokers compared to people who have never smoked,” said Meredith Duncan, MA, study author and PhD student at Vanderbilt University Medical Center in Nashville, Tennessee. “The bottom line is if you smoke, now is a very good time to quit.”