Certain Risk Factors Could Spur Heart Failure in Normal-Weight People
High blood pressure, cholesterol, insulin levels worse than obesity for some, study finds
WEDNESDAY, Sept. 14, 2011 (HealthDay News) -- Normal-weight patients diagnosed with a cluster of factors known as the "metabolic syndrome" could face a higher risk for heart failure than even obese patients without such factors, new research suggests.
Metabolic syndrome is characterized by a group of symptoms -- increased blood pressure, higher-than-normal insulin levels, excess body fat around the waist, high triglycerides and/or abnormal cholesterol levels -- that raise the risk of stroke, heart disease and diabetes.
A healthy metabolic profile, in turn, is marked by the absence of those symptoms, suggesting the major organs systems are in balance.
The new study suggests that being obese is not as much of a threat for heart failure as are those specific factors that typically contribute to a diagnosis of metabolic syndrome. These include having an "apple shape" (carrying extra weight around the middle and upper part of the body) and developing insulin resistance, leading to an unhealthful spike in blood sugar and blood lipid (fat) levels.
Study lead author Dr. Christina Voulgari, from the first department of cardiology at Athens University Medical School at Hippokration Hospital in Athens, Greece, said that the findings suggest that "we should focus not on weight loss at any given cost but (on) a healthier lifestyle" -- one, for example, that embraces exercise and eschews smoking.
Voulgari, also with Laiko General Hospital in Athens, and colleagues report their findings in the Sept. 20 issue of the Journal of the American College of Cardiology.
The authors explained that their investigation arose out of interest in those who are exceptions to the rule: those individuals who maintain a healthy metabolic profile despite being obese.
While metabolic syndrome and obesity more often than not go hand in hand, some obese patients buck the trend by retaining high insulin sensitivity, good blood pressure readings and positive glycemic, inflammation and lipid profiles.
But do such individuals, in turn, face a lower risk for heart failure than non-obese men and women who nonetheless struggle with the tell-tale signs of metabolic syndrome?
To explore the question, the research team tracked 550 men and women for an average of six years.
The patients were enlisted between 2003 and 2005, and none had a history of diabetes or signs of cardiac illness at the study launch.
Questionnaires were completed at the launch to gather information on health status, weight and body mass index, physical activity habits, and those factors that fall under the rubric of a metabolic syndrome evaluation.
As expected, the team found that about half of the participants had metabolic syndrome, and that obese patients were more likely to have it than those who were of normal weight or just overweight.
That said, the authors drilled down on the health status of those 185 patients, with an average age of just under 60, who ultimately experienced heart failure during the study period.
The results: heart failure risk appeared to be much higher among patients with metabolic syndrome than among those without, regardless of weight status. And, obese patients without metabolic syndrome were found to experience the lowest heart failure incidence rate of any category of patients.
For example, among patients who were not diagnosed with metabolic syndrome, heart failure incidence was roughly 9 percent among obese men and women, 14 percent among overweight patients, and 16 percent among those of normal weight.
This compared very favorably with patients who did have the metabolic syndrome. Among that group, heart failure incidence was much higher, hitting approximately 54 percent among the obese, 48 percent among the overweight, and 63 percent among those of normal weight.
The four metabolic syndrome factors associated with heart failure were impaired fasting glucose, low "good" HDL cholesterol, high blood pressure and excess abdominal fat (central obesity). Insulin resistance and inflammation -- also associated with metabolic syndrome -- were also independently linked to heart failure.
All told, having metabolic syndrome conferred a 2.5-fold greater relative risk for experiencing heart failure.
The team concluded that metabolic syndrome (and insulin resistance and inflammation, in particular) is a significant and independent marker of heart failure risk, and is more of a warning sign than obesity alone.
Commenting on the study, Dr. Robert Scott III, an associate professor of internal medicine at Texas A&M Health Science Center College of Medicine and a senior staff cardiologist at Scott & White in Temple, Texas, said the findings clearly suggest that metabolic syndrome "is the bad actor at play."
"Yes, in general, obesity is a bad thing," he noted. "But it's not everything. And here we have a bit of fine-tuning that suggests that the important thing with obesity tends to be the metabolic syndrome."
"And that means," Scott added, "that if you have this constellation of factors -- high blood pressure, low HDL, high sugar levels -- you are going to face a much higher risk for coronary heart disease and congestive heart failure. Even if you're not obese."
But Dr. Gregg C. Fonarow, a professor of cardiovascular medicine at University of California, Los Angeles, said that while the study drives home the notion that metabolic risk factors are key to heart disease risk, obesity is still a problem.
A Scottish study published earlier this year in the journal Heart, for example, indicated that obese men face a much higher risk of dying from a heart attack, whether or not they also struggle with independent cardiovascular risk factors such as high blood pressure and high cholesterol.
The Greek researchers "are just looking at heart failure here," he noted. "But obesity also comes along with a higher risk for diabetes, cancer and shortened survival overall. So it's not that one's overall health in the long-term will not be adversely affected by being obese. Getting to a healthy body weight, of course, remains as important as ever."
For more on the metabolic syndrome, visit the U.S. National Library of Medicine.