Does genetics explain why so few of us have an ideal cardiovascular health?

In 2009, the American Heart Association introduced the notion of “ideal cardiovascular health”, which is based on seven potentially modifiable risk factors for cardiovascular disease (CVD): not smoking, having a healthy diet, being physically active, having a normal body mass index, having a normal blood pressure as well as blood sugar and cholesterol levels. Since then, the results of a handful of large scale prospective studies have suggested that meeting the criteria for ideal cardiovascular health could help reduce the risk of CVD by up to 90% in men and women. These reports have also underscored that only between 0.1 and 5% of the general population actually achieve ideal cardiovascular health, which probably explains why CVD still remains the leading cause of mortality worldwide. Understanding the factors that could explain why some are more likely to achieve ideal cardiovascular health than others is therefore critical to design interventions aiming at improving ideal cardiovascular health in the population. Although decades of research in the field has suggested that behavioural factors and socioeconomic status could be tied to features of ideal cardiovascular health, the contribution of genetic factors to ideal cardiovascular health is completely unknown.

In order to determine whether genetic factors could actually contribute to ideal cardiovascular health, investigators from the United States and Canada analyzed the results of four studies included in the CHARGE (Cohorts of Heart and Aging Research in Genome Epidemiology) consortium. Together, these cohorts included close to 12,000 men and women with data on the seven components of ideal cardiovascular health. Interestingly, a genome-wide scan that tested the association between 2.5 million common variants and ideal cardiovascular health identified only one genetic variant associated with ideal cardiovascular health. This variant in a gene called APOE had previously been linked to blood cholesterol levels in the past. Results of this study (published in the American Heart Journal) show that although genetic variants could be associated with some parameters of ideal cardiovascular health such as blood cholesterol levels, their contribution to overall ideal cardiovascular health is very minor.

There are many barriers to achieving ideal cardiovascular health. For instance, cost of medications, poor access to health care, high-quality foods, safe facilities to exercise, and a low socioeconomic status are contributors to poor cardiovascular health. What this study suggests is that genetic factors do not explain why some people do not have ideal cardiovascular health. In other words, one’s zip code is probably more relevant to predict poor cardiovascular health than one’s genetic code. Interventions aiming at breaking the barriers that stand in the way of achieving ideal cardiovascular health by focusing on lifestyle habits should therefore provide substantial benefits to reduce the burden of CVD around the world.