Obesity and Subclinical Heart Disease

When a patient meets certain set criteria for a disease or condition, we doctors say that they have clinical [disease or condition]. For example, the World Health Organization and the National Institute of Health have designated a Body Mass Index of 30 or more as clinically obese. On the other hand, with some conditions a patient might have the condition, yet not show symptoms, and that is called subclinical [condition]. I have heard, for example, of marathon runners and dedicated bicyclists who dropped dead of heart attacks because they had subclinical heart disease.

But runners and bicyclists who still have heart disease despite their healthy lifestyle are the exception rather than the rule. A study published in the Archives of Internal Medicine (2008;168(9):928-935) looked at the relationship between subclinical heart disease and Body Mass Index across several ethnic groups.

The Multi-Ethnic Study of Artherosclerosis included over 6800 men and women between the ages of 45 and 84 who had not been diagnosed with cardiovascular disease. The researchers used questionnaires to find out about their volunteers' medical history and any medications they used, then measured their height and weight (for Body Mass Index) and took blood pressure readings as well as blood samples for cholesterol tests.

In addition, each subject received specialized tests to assess more subtle measures of cardiovascular disease: the amount of calcium in their coronary arteries, whether the walls of their arteries were thickened, and whether the left ventricle of their heart was enlarged. These more thorough and much more expensive tests pick up the otherwise hidden symptoms of heart disease.

Armed with the results of the tests, the researchers could then correlate the Body Mass Index of each subject with their blood pressure, fasting glucose levels, and cholesterol scores, along with the heart disease symptoms from the more specialized tests. They found that compared to those of normal body weight, those who were overweight were 20% more likely to have thickened arterial walls and 65% more likely to have enlarged ventricles. Those who were obese were almost 30% more likely to have thickened arterial walls and over two times as likely to have enlarged ventricles.

What this means for you

Maybe you're overweight but feel fine. Maybe your blood pressure's a little high, but not alarmingly so. Maybe your cholesterol levels aren't bad, just… not great. You could still have very serious risk factors developing in your heart. Maintaining a body weight in the normal range for your height is one of the most powerful things you can do for your heart's health.

First posted: January 28, 2009