Body Mass Alone Doesn’t Tell Heart Risk
http://www.medpagetoday.com/MeetingCoverage/ESC/41400
Published: Sep 5, 2013
By Todd Neale, Senior Staff Writer, MedPage Today
AMSTERDAM — A press conference highlighting four studies presented here at the European Society of Cardiology meeting tackled the so-called obesity paradox, in which a high body mass index (BMI) appears to be protective in certain populations.
Bigger Waists Predict Death in Heart Attack Survivors
Abdominal obesity — measured using waist circumference — was a better predictor of 5-year mortality among French survivors of an acute myocardial infarction (MI) than was BMI, according to a study presented by Tabassome Simon, MD, of Hôpital Saint Antoine in Paris.
She and her colleagues examined data from the French FAST-MI registry, which followed patients discharged following an acute MI for 5 years. The analysis included 3,102 patients with BMI recorded and 1,647 with waist circumference recorded.
Looking at BMI, there was an increased risk of dying for those with the lowest body mass (less than 22 kg/m2) and those with the highest (35 kg/m2 and higher), but not for those in the middle of those two groups, which included individuals who were overweight and mildly obese.
Within each category of BMI, however, increased waist circumference was associated with an elevated risk of dying within the follow-up period. After adjusting for BMI in a multivariate analysis, waist circumference in the upper quartile was associated with a 44% greater risk of dying through 5 years (HR 1.44, 95% CI 1.16-1.79).
“Waist circumference is definitely a better indicator of mortality,” Simon said.
“From a public health standpoint, educational messages may focus on the most severe forms of obesity and on abdominal obesity, as well as on other modifiable risk factors, rather than overweight and mild obesity,” she said.
Metabolic Health an Important Sign of Heart Health
Whether young women had metabolic disorders was more predictive of the risk of heart attack and ischemic stroke than was BMI, a large Danish study showed.
Michelle Schmiegelow, MB, of Gentofte Hospital in Copenhagen, and colleagues examined data from 261,489 young, fertile women (median age 30.5) who didn’t have a prior history of cardiovascular disease. The women were divided into four groups based on BMI either above or below 25 kg/m2 and on the presence of metabolic disorders, including hypertensive disorders, glucose metabolism disorders, and elevated cholesterol.
Through a median follow-up of 5.5 years, the rate of MI or ischemic stroke was lowest among the women who had a normal weight and were free from any of the metabolic disorders (16.7 per 100,000 person-years).
Compared with them, the risk of MI or stroke was elevated among the women who had at least one of the metabolic disorders, regardless of BMI. The risk was not higher, however, among the women who were overweight but metabolically healthy.
“It seems like the increased cardiovascular risk associated with obesity lies in the metabolic health,” Schmiegelow said. “There might be a window of opportunity in which … metabolically healthy overweight or obese women can change their lifestyle and thereby reduce their risk of developing metabolic disorders and thereby possibly reduce their risk of heart attack and ischemic stroke substantially.”
Low BMI Tied to Higher Heart Risk
In patients with hypertension and diabetes, the risk of cardiovascular events was highest among those with the lowest body mass, a Japanese study showed.
Takanori Nagahiro, MD, of Nagoya University Hospital in Japan, and colleagues used data from the Nagoya Heart Study — a randomized trial comparing valsartan (Diovan) and amlodipine in patients with hypertension and glucose intolerance — to explore the relationships between BMI and the risk of cardiovascular disease. The researchers divided the 1,105 patients included in the current analysis into four BMI groups — less than 23, 23 to less than 25, 25 to less than 27.5, and 27.5 kg/m2 or greater.
The rate of acute MI, stroke, heart failure hospitalization, coronary revascularization, or sudden death through a median follow-up of 3.2 years declined from the lowest BMI group to the highest. The rates per 100 person-years were 4.6, 2.3, 2.8, and 1.5 (P=0.001).
Nagahiro cautioned, however, that the findings might be explained by the presence of more severe diabetes in the patients with the lowest BMI, indicated by more frequent use of insulin.
Weight Loss Signals Death Risk in Women with Heart Disease
Independent of starting BMI, weight loss was associated with shortened survival among women with coronary heart disease, according to a study presented by Aziza Azimi, MB, of Gentofte Hospital in Copenhagen.
She and her colleagues retrospectively examined data from 1,685 women who had heart disease confirmed with angiography from 2005 to 2011. Follow-up lasted up to 6 years.
Weight loss — defined as a drop in body weight of more than 2 kg (4.4 lbs.) in a year — was associated with a greater risk of dying during follow-up in normal-weight women (HR about 3), overweight women (HR about 6), and obese women (HR about 9). Weight gain was associated with an increased mortality risk in obese women only.
Because the study was retrospective, there was no information on why the women in the study lost weight, but Schmiegelow, the researcher from one of the other studies presented, noted that in a heart disease population, weight loss can reflect worsening disease status.
What Does It All Mean?
Diethelm Tschoepe, MD, of the Heart and Diabetes Center North Rhine-Westphalia in Germany, who served as one of the moderators of the press conference, said the overall message of the four studies was “that adiposity is a very complex disease where body weight is one dimension, but it’s not the only dimension which determines the prognosis.”
Body composition and risk factor burden also contribute to disease risk, he noted.
“In other words, the world is completely different whether you are a young otherwise healthy individual and you are talking about body weight or whether you are a patient with coronary heart disease or congestive heart failure talking about the same body weight,” he said.
He indicated that the message for patients is not clear.
“In the moment I would like to stay with the guidelines here that stabilization of body weight in a given class seems to be at least a defensive strategy with all these incoming data,” Tschoepe said.