Headed for a Dangerous Change of Heart?

If you're relatively young and relatively healthy, preventing heart failure may not be a top priority, even though cardiovascular disease remains the No. 1 killer of Americans.

But as research continues into what causes heart failure and how to best prevent it, an ominous and telling picture has emerged: The heart itself can change in dangerous ways long before a person ever experiences any outward symptoms or notices signs of trouble. Particularly if under stress -- like from uncontrolled high blood pressure -- the heart can become abnormally enlarged, a condition called left ventricle hypertrophy. This makes the heart less efficient at pumping blood, and can ultimately lead to life-threatening heart failure.

So while a focus on being heart healthy has become part of the national consciousness, experts say more emphasis still needs to be placed on making changes early -- from checking and controlling high cholesterol to improving diet -- to prevent an irreversible, potentially deadly change of heart later. "Because once there's structural changes [to the heart], the bell's been rung and we don't have good therapies to roll the effects of 20 to 30 to 40 years back," says Dr. Xavier Prida, an assistant professor of medicine in the department of cardiovascular sciences at the University of South Florida Morsani College of Medicine in Tampa.

He says lifestyle improvement and medical interventions, where needed, should occur before people reach midlife and develop symptoms of heart failure -- which range from shortness of breath to fluid buildup in body tissues, causing swelling in places like the feet or ankles. As a starting point, Prida highlights the tried and true steps to improve heart health laid out by the American Heart Association, which the organization dubs Life's Simple 7: manage blood pressure, control cholesterol, reduce blood sugar, get active, improve diet, lose weight and quit smoking.

In addition to those proven methods of prevention, research is also underway to better understand what causes changes in the heart and how to stop the damage from occurring before it proves fatal. In September, the National Institutes of Health awarded a four-year, $1.9 million grant to support research at the University of Virginia School of Medicine in Charlottesville that explores a real sweet heart of a question: Can the heart become addicted to blood sugar -- and can blocking that addiction prevent cardiac hypertrophy, the dangerous abnormal enlargement of the heart that can lead to heart failure?

While sugar has fast become a villain in the national discussion about cardiovascular risk factors, the research led by Bijoy Kundu, an assistant professor of radiology and medical imaging at the UVA School of Medicine, is a twist on that theme. Under normal circumstances the heart metabolizes fatty acids for fuel, only turning to blood sugar for quick energy in the short-term, says Kundu, who is also a faculty member at the UVA Robert M. Berne Cardiovascular Research Center. But in cases where the heart is chronically stressed, caused by things like uncontrolled high blood pressure, the heart may begin gorging itself on blood sugar, he explains.

"We have shown that in response to high blood pressure the heart needs more fuel to function normally and looks for easy energy, thereby increasing its usage of glucose," Kundu says. It's not terribly unlike what you could be doing right now -- binging on office cookies to get by while under pressure from your boss and deadlines. And just as eating too much dessert can cause you to swell, Kundu's team hypothesizes that the heart's longer-term switch to using blood sugar for fuel, instead of fatty acids, triggers the development of left ventricular hypertrophy, which leads to enlargement of the heart, the thickening of its walls and eventual heart failure.

So, using nuclear imaging and evaluating rats, UVA researchers want to see if they can identify when the heart's fateful switch to metabolizing glucose takes place. Once they identify that "therapeutic window," they plan to test the diabetes drug metformin, which suppresses glucose production by the liver, to see if that might prevent potentially fatal changes to the structure and function of the heart. "There is a lack of effective medical therapies to treat cardiac hypertrophy due to hypertension and ... early detection and prevention are important," Kundu says.

To avoid confusion, he emphasizes that the study is not looking at what happens to the heart when a person consumes a lot of sugar -- like eating unhealthy snacks and drinking sweetened beverages -- a focal point of other research. But as with those studies, the impetus behind the UVA research is similar in a broader sense: figure out what factors lead to irreparable heart damage to better understand how to prevent it long before a person experiences shortness of breath, wheezing, irregular heartbeat -- or worse. Says Kundu: "The key is to identify this early on."

Michael Schroeder is a health editor at U.S. News. You can follow him on Twitter or email him at mschroeder@usnews.com.