Smokers with the most common type of heart rhythm disorder can reduce their risk of stroke and death by giving up cigarettes, a new study says.

“Smoking precipitates blood clots that could lead to a stroke, which may be why giving up lowers risk,” said study author So-Ryoung Lee of Seoul National University Hospital in South Korea.

But even former smokers had higher odds for stroke compared to never smokers, the study found.

“The remaining stroke risk after quitting might be through the damage already caused to the arteries — called atherosclerosis,” Lee said in a European Society of Cardiology news release.

Stroke is the most common cause of death in people with atrial fibrillation (a-fib). People with a-fib are five times more likely to have a stroke than those without the heart rhythm disorder. And a-fib increases the risk of death two-fold in women and 1.5-fold in men.

Previous research has shown that smokers are at higher risk for a-fib and a subsequent stroke.

This study included nearly 98,000 people, average age 61, in South Korea who were diagnosed with a-fib from 2010 to 2016. They were followed until the end of 2017, for a median follow-up of three years.

Compared to current smokers, quitters were 30% less likely to have a stroke and 16% less likely to die from any cause.

However, quitters were still 19% more likely to have a stroke and 46% more likely to die than people who never smoked, but these associations were consistently seen only in men.

New and persistent smokers had even greater risk of stroke than people who never smoked. New smokers had an 84% higher risk and persistent smokers had a 66% higher risk, according to the study. The results were presented Tuesday at a virtual meeting of the European Society of Cardiology.

Lee noted that the benefits of quitting were less pronounced in people who were heavy smokers before their irregular heartbeat diagnosis.

“This may be related to longer-term damage to the blood vessels which increases susceptibility to having a stroke,” Lee said.

“If you don’t smoke, don’t start. If you do, it’s never too late to quit. Regardless of how much you smoke, kicking the habit is good for health,” Lee concluded.

Data and conclusions presented at meetings are usually considered preliminary until peer-reviewed for publication in a medical journal.

More information

The U.S. National Heart, Lung, and Blood Institute has more on a-fib.