Dr Martin Juneau, M.D., FRCP
Cardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.See all articles
Updated on December 19, 2018
It has been known for several years that there is a genetic predisposition to coronary heart disease. For example, if one of the parents of a person has died prematurely of a heart attack, the risk of that person being affected by a coronary event is higher than the general population. Family history of cardiovascular disease is an important risk factor and is therefore one of the first questions asked by a cardiologist during a consultation.
Genome-wide association studies have led to a better understanding of this phenomenon. These studies consist of identifying the genetic variations present in the genome of a large number of individuals, and then determining if these variations can be correlated with certain traits, for example the premature development of cardiovascular disease. As a result of these studies, researchers have identified more than 50 DNA regions associated with an increased risk of coronary heart disease, and thus they represent a marker of a person’s genetic predisposition to these diseases.
Does this mean that people who have the misfortune of being born with these “bad genes” are doomed to die prematurely from coronary heart disease? According to a remarkable study recently published in The New England Journal of Medicine, the answer is no: even if these genetic variations double the risk of cardiovascular disease, adopting a healthy lifestyle can significantly reduce this increased risk. In fact, the authors found that simply adhering to a healthy lifestyle (not smoking, doing moderate physical activity, and eating plenty of fruits, vegetables, and whole grains) allows people at high risk to halve the risk of coronary events. And the opposite is true: people who have genes that theoretically should protect them from coronary heart disease but who adopt an unhealthy lifestyle see their risk of developing these diseases increase by 50%. A similar phenomenon is observed for stroke, i.e., that a healthy lifestyle greatly reduces the risk of stroke, whatever the genetic predisposition.
It appears that regular physical exercise is an essential part of this risk reduction in people who are genetically predisposed: a study recently showed that people at high risk but who had the best cardiorespiratory fitness had 49% less risk of being affected by coronary artery disease and 60% less risk of being affected by atrial fibrillation episodes than those who were not as physically fit.
These observations illustrate the extent to which the diseases that affect us are the result of a complex interaction between our genes and our environment. Everything is not decided at birth: one can be born with a gene that predisposes to cardiovascular diseases, but these genes are only one of the aspects involved in the development of these diseases, a predisposition which is very real, but which nevertheless remains strongly influenced by a host of external factors.
It is therefore possible to take charge of our destiny, to change our lifestyle to neutralize the negative impact of these bad genes. Not smoking, eatingavarietyofplant foodsinabundance, maintaining a healthy body weight, and exercising regularly are all actions that actually prevent coronary heart disease, regardless of the basic genetic risk.