Heart Risks and Metabolic Syndrome Linked
A cluster of cardiac factors known as "metabolic syndrome" is a strong indicator of increased risk of heart disease, according to a report in the Journal of the American College of Cardiology (JACC).
Metabolic syndrome includes factors such as lower-abdomen obesity, high blood pressure, blood fat disorders such as high LDL ("bad") cholesterol, and insulin resistance or elevated blood sugar levels.
Generally, someone with three or more of these factors is said to have metabolic syndrome.
"The question has been for a number of years what the risk associated with metabolic syndrome is," says study author Dr. Apoor S. Gami, an assistant professor of medicine at the Mayo Clinic College of Medicine.
"What is the quantified risk in patients with metabolic syndrome? That is one question we could answer by meta-analysis," says Dr. Gami.
A meta-analysis crunches data from a host of prior studies to come to a more solid conclusion.
This analysis of 37 studies included more than 170,000 individuals. Dr. Gami not only analyzed published studies, but also sought more detailed information from the researchers who did the studies.
The meta-analysis found the risk of heart attack or death was 78 percent higher for people with metabolic syndrome than those who did not have this constellation of risk factors.
"The main take-away from this study is that people identified with metabolic syndrome, regardless of the criteria used to describe metabolic syndrome, are at increased risk of cardiac events or death," explains Dr. Gami.
"There is anywhere from a 50 percent to 200 percent increase in risk, which seems to be stronger in women," he says.
The implication for medical practice is that anyone with metabolic syndrome needs extra attention for preventive measures, says Dr. Gami.
The finding comes as something less than a surprise, notes Dr. Robert Eckel, a professor of medicine at the University of Colorado.
"Many of us in the field have felt that it [metabolic syndrome] is important for some time now," says Dr. Eckel.
But there is ongoing debate about "how you define metabolic syndrome in terms of threshold values," he says. "This is a syndrome, not a disease. We still need to learn more about its components and how we can define them better."
While Dr. Eckel says the new study provides "additional evidence for the value of metabolic syndrome," a dissenting view came from Dr. Michael Stern, at the University of Texas Health Science Center at San Antonio.
He has written skeptical reports on the importance of metabolic syndrome, including one for the American Diabetes Association.
"There is no doubt that metabolic syndrome is associated with increased cardiovascular risk," says Dr. Stern. "The question is whether it is the best way to identify that risk.
"There are other established methods of identifying high-risk individuals that are not related to metabolic syndrome," he says.
According to Dr. Stern, an equation derived from the long-running Framingham Heart Study provides a better risk assessment than the metabolic syndrome, which is "an arbitrary collection of risk factors.
"If the goal is to identify high-risk individuals, you can do just as well or better with the Framingham equation," he says.
But the presence of the metabolic syndrome provides better evidence of risk than taking individual components of the syndrome one by one, Dr. Gami counters.
"Three studies addressed this, and the risk was increased by 50 percent above those of the individual risk factors that were present," says Dr. Stern.
Always consult your physician for more information.
Metabolic syndrome is a condition that includes the presence of a cluster of risk factors specific for cardiovascular disease.
Metabolic syndrome significantly raises the risk of developing diabetes, heart disease, and/or stroke.
Most people who have metabolic syndrome have insulin resistance.
The body makes insulin to move glucose (sugar) into cells for use as energy.
Obesity, commonly found in persons with metabolic syndrome, makes it more difficult for cells to respond to insulin. If the body cannot make enough insulin to override the resistance, the blood sugar level increases and diabetes can result.
Metabolic syndrome may be a beginning of the development of type 2 diabetes.
The cluster of conditions and risk factors related to metabolic syndrome was first named in 1988. Dr. Gerald Reaven proposed that insulin resistance was central to the cause of type 2 diabetes, high blood pressure, and cardiovascular artery disease.
Dr. Reaven called this cluster of abnormalities "Syndrome X." Since that time, Syndrome X has come to be known by various names, including metabolic syndrome, dysmetabolic syndrome, and insulin resistance syndrome. Syndrome X is now widely known as metabolic syndrome.
The American Heart Association (AHA) recognizes metabolic syndrome as a problem of growing concern.
For those over age 60, the percentage is estimated to be about 43 percent. Because the population of the US is aging and because metabolic syndrome prevalence increases with age, the AHA has estimated that metabolic syndrome soon will become the primary risk factor for cardiovascular disease, ahead of cigarette smoking.
Increasing rates of obesity are also thought to be related to the increasing rates of metabolic syndrome.
The cluster of metabolic factors involved as defined by the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) report, sponsored by the National Heart, Lung, and Blood Institute, includes:
- abdominal obesity, in which the waist circumference measures more than 35 inches for women and more than 40 inches for men - an increased waist circumference is the form of obesity most strongly associated with metabolic syndrome.
- high blood pressure of 130/85 mm Hg (millimeters of mercury) or higher - normal blood pressure is defined as 120 mm Hg or lower for systolic pressure (the top number), and 80 mm Hg or lower for diastolic pressure (the bottom number). High blood pressure is strongly associated with obesity and is often found in persons with insulin resistance.
- insulin resistance - a condition in which being overweight or obese makes it hard for cells to respond to insulin. The body releases more insulin to help glucose enter the cells until blood sugar increases. Insulin resistance can lead to diabetes.
- high triglyceride levels of more than 150 mg/dl (milligrams per deciliter) - triglycerides are a type of fat in the blood
- HDL cholesterol (the "good" cholesterol) of less than 40 mg/dl for men and less than 50 mg/dl for women
- proinflammatory state - a condition that involves elevated C-reactive protein, a substance that is thought to be a marker for inflammation in the body
- prothrombotic state - a condition that involves elevated blood clotting factors
Always consult your physician for more information.