BARCELONA, Spain — Cigarettes have become synonymous with lung cancer, but troubling new research finds a daily smoking habit is even more damaging to the heart than previously thought. Studies have shown for some time that smoking can damage blood vessels and block arteries, but this latest work reveals smoking actively harms the heart itself.

Study authors say the more people smoke, the worse their heart function becomes. On a positive note, “some” heart function did return after smokers quit the habit.

“It is well known that smoking causes blocked arteries, leading to coronary heart disease and stroke,” says study author Dr. Eva Holt of Herlev and Gentofte Hospital in a media release. “Our study shows that smoking also leads to thicker, weaker hearts. It means that smokers have a smaller volume of blood in the left heart chamber and less power to pump it out to the rest of the body. The more you smoke, the worse your heart function becomes. The heart can recuperate to some degree with smoking cessation, so it is never too late to quit.”

WHO: Smoking kills millions each year

According to the World Health Organization, tobacco is responsible for more than eight million deaths annually. More specifically, cigarette smoke displays a connection to 50 percent of all avoidable deaths among smokers, and half of those deaths are a result of atherosclerotic cardiovascular diseases (heart attacks and stroke). So, suffice to say, science has firmly established the negative impact of smoking on arteries and arterial diseases.

Meanwhile, other studies have found an association between smoking and a higher risk of heart failure. During heart failure, the heart muscle stops pumping blood throughout the body as efficiently as it should. Consequently, the body does not receive all the oxygen and nutrients it needs. This condition is usually due to a weak or stiff heart.

However, the link between smoking and heart structure or function hasn’t been explored all that thoroughly by researchers up until now. The research team investigated whether or not smoking is directly related to fluctuations in both the structure and functioning of the heart among people with no history of any cardiovascular disease, as well as the effect of changing one’s smoking habits.

Smokers develop ‘thicker, heavier and weaker hearts’

Study authors analyzed data provided by the 5^th Copenhagen City Heart Study for this project. That dataset encompassed 3,874 people of various ages (20-99 years-old) without heart disease at the time of enrollment. The group completed a self-administered questionnaire that asked about their personal smoking history and habits. The survey also asked participants to estimate their “pack-years,” which refers to the number of cigarettes smoked throughout their entire life. One pack-year is the same as 20 cigarettes smoked every day for a full calendar year.

All participants also underwent an ultrasound of their heart (echocardiography), which revealed valuable information pertaining to its structure and working efficiency. The researchers then compared echocardiography results of current smokers against never-smokers. Importantly, researchers were sure to adjust for various factors such as age, sex, body mass index, hypertension, high cholesterol, diabetes, and lung function before making those comparisons.

The average age among subjects was 56 years-old, and 43 percent were female. Close to one in five were current smokers (18.6%). Meanwhile, another 40.9 percent were former smokers, and 40.5 percent never smoked. In comparison to never-smokers, current smokers displayed thicker, weaker, and heavier hearts. Moreover, more pack-years showed a connection with pumping less blood.

“We found that current smoking and accumulated pack-years were associated with worsening of the structure and function of the left heart chamber – the most important part of the heart. Furthermore, we found that over a 10-year period, those who continued smoking developed thicker, heavier and weaker hearts that were less able to pump blood compared to never smokers and those who quit during that time,” Dr. Holt explains.

“Our study indicates that smoking not only damages the blood vessels but also directly harms the heart. The good news is that some of the damage is reversible by giving up,” the researcher concludes.

The study authors presented their findings at ESC Congress 2022.