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Smokers have weaker hearts that pump less blood

Although we are familiar with the association between smoking and lung cancer, a new study that investigates the effect of smoking on heart structure and function is to be presented at the European Society of Cardiology Congress 2022. The Congress takes place between 26 and 29 August, 2022, in Barcelona, Spain. The study finds that smokers have weaker hearts than non-smokers, and that the more a person smokes, the worse his or her heart function becomes. 

“It is well known that smoking causes blocked arteries, leading to coronary heart disease and stroke,” said study author Dr. Eva Holt of Herlev and Gentofte Hospital. “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.”

Tobacco kills more than eight million people each year, according to the World Health Organization. Cigarettes are responsible for 50 percent of all avoidable deaths in smokers, with half of these due to atherosclerotic cardiovascular diseases such as heart attack and stroke. 

Studies have also shown that smoking is associated with a higher risk of heart failure, and that this is often caused by a weakened heart muscle that does not pump blood around the body adequately. Where a weakened heart does not pump as much blood as it should, the cells of the body will not receive the oxygen, glucose or other nutrients they need in order to function. However, the link between smoking and heart structure and function has not yet been fully examined.

In the current study, the researchers explored whether smoking was related to changes in the structure and function of the heart in people without cardiovascular disease, as well as investigating the effect of changing smoking habits. Data from the 5th Copenhagen City Heart Study was used; this study investigated cardiovascular risk factors and diseases in the general population. A total of 3,874 participants who had no heart disease were enrolled in the study and they were categorized as current smokers, former smokers or never smokers. 

The participants, who were aged between 20 and 99 years, were required to complete a self-administered questionnaire that asked for details of smoking history, and to estimate their pack-years, which is a measure of the number of cigarettes smoked throughout life. One pack-year is defined as 20 cigarettes smoked every day for one year.

Participants also underwent an ultrasound examination of the heart, called echocardiography, which gave information about its structure and how well it was working. The researchers compared the echocardiography measures of current smokers to those who had never smoked, while taking into account the participants’ age, gender, body mass index, blood pressure, cholesterol levels, diabetes status and lung function.

The average age of participants was 56 years and 43 percent of them were women. Nearly one in five participants (18.6 percent) currently smoked, while 40.9 percent were former smokers and 40.5 percent had never smoked. Compared to never smokers, current smokers had thicker, weaker and heavier hearts. In addition, less blood was pumped by the hearts of people who had high values for pack-years.

“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,” explained Dr. Holt. 

“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.”

“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.”

By Alison Bosman, Staff Writer

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