The arteries in our body are lined with a layer of cells called the endothelium. The very first step in the development of cardiovascular disease—the primary cause of heart attack and stroke—takes place when the endothelium begins to function abnormally. In research presented at the Canadian Cardiovascular Congress in Vancouver, physicians at the University of Ottawa Heart Institute and the Mayo Clinic have found that long-term weight gain triggers this endothelial dysfunction independently of other risk factors for heart disease. “There are many metabolic changes associated with weight gain that promote dysfunction of the arteries and, down the road, promote heart attack and stroke,” said Heart Institute cardiologist Thais Coutinho, MD, lead author on the study.
Arteries are more than simple tubes for delivering blood throughout the body. They expand and contract to impact blood flow, they play a role in coagulation and clotting, and they participate in immune responses. Endothelial dysfunction is marked by signs of chronic inflammation and a reduced capacity for arteries to expand. Once this happens, it may then take years for plaques and blockages to form in artery walls. The study looked at 521 men and women with no history of heart attack or stroke. Weight, waist circumference, percentage of body fat, and other measures were taken for each participant at the start of the study and again 8.5 years later. Endothelial function was measured non-invasively using ultrasound of the brachial artery. Individual factors that could impact the results were accounted for. These included age, sex, smoking and use of cholesterol or blood pressure medications. Increases in weight, waist circumference and percentage of body fat were associated with the presence and extent of endothelial dysfunction. Weight gains of more than 10 kg resulted in the greatest impairment of function. Individuals that maintained their weight or had only small increases actually showed improved endothelial function over time. This impact of weight gain was independent of other risk factors for heart disease. “Some of our own previous studies in patients that had established coronary artery disease (blockage in the arteries of the heart) found that obesity of the waist was associated with more deaths,” explained Dr. Coutinho. “Now, we are finding that, if you don’t have established vascular disease, weight gain also has negative consequences. Once the atherosclerotic cascade begins, it is very difficult to stop it; therefore, preventing arterial disease from happening in the first place is extremely important. Our study highlights the importance of maintaining a healthy lifestyle and a healthy weight in order to prevent the abnormalities that can ultimately lead to arterial disease.”