An unhealthy lifestyle may have a bigger role to play in the development of premature heart disease than genetics, a new study suggests.

According to European researchers, while genetics are undoubtedly "an important contributor" to heart disease that occurs in people under the age of 50, they "should not be used as an excuse to say it is inevitable".

"In our clinical practice, we often hear young patients with premature heart disease ‘seek shelter' and explanations in their genetics/family history. However, when we look at the data in our study, these young patients were frequently smokers, physically inactive, with high cholesterol levels and high blood pressure - all of which can be changed," commented the study's author, Dr João Sousa of Funchal Hospital in Portugal.

The study involved 1,075 patients under the age of 50, around half of whom had premature coronary artery disease, which included conditions such as angina and heart attack.

The average age of the participants was 45 and they were compared to a similar number of healthy volunteers with an average age of 44.

Five modifiable risk factors were assessed - physical inactivity, high blood pressure, smoking, high cholesterol and diabetes.

The study found that 73% of the people with coronary artery disease had at least three of these risk factors compared to 31% of the healthy volunteers. However, in both groups, the likelihood of developing heart disease increased significantly with each additional risk factor.

In fact, the probability of coronary artery disease was three times higher if the person had one additional risk factor, seven times higher if they had two additional risk factors, and 24 times higher if they had three or more risk factors.

An assessment of the participants' genetics also revealed that while those with coronary artery disease had a higher genetic risk score that those without the condition, the contribution of genetics to the risk of coronary artery disease started to decline as the number of modifiable risk factors rose.

"The findings demonstrate that genetics contribute to coronary artery disease. However, in patients with two or more modifiable cardiovascular risk factors, genetics play a less decisive role in the development of the disease.

"Our study provides strong evidence that people with a family history of premature heart disease should adopt healthy lifestyles, since their poor behaviours may be a greater contributor to heart disease than their genetics. That means quit smoking, exercise regularly, eat a healthy diet, and get blood pressure and cholesterol levels checked," Dr Sousa said.

Details of these findings were presented at the European Society of Cardiology Congress 2019 together with the World Congress of Cardiology in Paris, France.