Strong Heart study (SHS): Bigger, heavier hearts portend heart disease risk even before adulthood
Jun 3, 2006 - 8:59:37 AM
The effects of excess weight on heart health can be seen even in adolescents, with abnormal enlargement and impaired pumping function evident in subjects by age 20, according to a new study in the June 6, 2006, issue of the Journal of the American College of Cardiology.
"Heart damage starts very early in the natural history of obesity. We need to work on our young people, to prevent catastrophic effects later on," said Giovanni de Simone, M.D., F.A.C.C. from the New York Presbyterian Hospital-Weill Medical College of Cornell University in New York, New York and the Federico II University Hospital School of Medicine in Naples, Italy.
The Strong Heart study (SHS) is a longitudinal study of cardiovascular risk factors and cardiovascular disease that enrolled 4,549 people in American Indian communities in Arizona, Oklahoma, and North and South Dakota. This analysis included data from examinations of 460 participants age 14 to 20 years (245 girls and 215 boys). The researchers used ultrasound and other methods to measure the size, shape and pumping function of the teenagers' hearts.
The left ventricles of the hearts of both overweight and obese teenagers were larger and heavier than those of normal weight participants; but the obese teenagers also showed signs of impaired heart function. The changes were not entirely explained by changes by high blood pressure.
"Our findings demonstrate that, even among adolescents at a mean age under 18, severity of abnormality in body build also parallels early cardiac changes, including high prevalence of left ventricular hypertrophy and increased hemodynamic load, paralleling previous findings and suggesting that increased left ventricular mass occurs to sustain the increased cardiac workload," the study authors wrote.
"The main findings are that, when obesity is present, something happens in our hearts to increase its size and wall thickness, which cannot be understood by measurement of blood pressure. This excess of cardiac mass, which we call 'inappropriate' in connection to cardiac workload, is also associated with a general impairment of the function of the heart to push blood into the arterial tree and also to distend its cavity to receive the blood returning from the periphery," Dr. de Simone said.
He said that these results underscore the need to fight excess weight in children, since the damaging effects are evident even before adulthood.
Although the participants in this study were all members of American Indian communities, Dr. de Simone said that he believes similar effects would be seen in overweight and obese children from other communities.
"The analysis was performed in an American Indian population and whether these results can be generalized to other ethnic groups needs to be demonstrated. However, similar analyses previously performed in other ethnic groups, such as Caucasians and African Americans, have suggested similar association between left ventricular mass and adiposity, independently of other cardiovascular risk factors," the authors wrote.
In an editorial in the journal, Stephan von Haehling, M.D., Wolfram Doehner, M.D., Ph.D., and Stefan D. Anker, M.D., Ph.D. from the Imperial College School of Medicine in London, United Kingdom and the Charité Medical School and Campus Virchow-Klinikum in Berlin, Germany wrote that the results from this study are in line with those from other studies that have documented that overweight and obese children and adolescents tend to have enlarged hearts and that enlarged hearts are a sign of increased risk of chronic heart failure.
"But patients with chronic heart failure, who have a poor prognosis per se, appear to benefit from being overweight. The most intriguing question in this respect is to define a time point after which obesity does not pose as a risk factor anymore," the editorial authors wrote.
"For young people with presence of established risk factors for future cardiovascular illness (like hypertension, hyperlipidemia or diabetes), it seems very likely that obesity confers a somewhat higher risk for death compared with such people with normal weight. Whether the same is true for older people is not known. We hypothesize that obesity carries no adverse mortality impact above the age of 60 years--possibly even from age 55 to 50 years. This remains to be tested," they added.
Robert J Bryg, M.D. from the University of Nevada School of Medicine, who was not connected to this study, said it demonstrates that there are significant cardiac consequences of childhood obesity.
"The increased left ventricular mass and left ventricular hypertrophy would suggest that long term consequences will occur in this cohort. Even though this is a population of Native Americans, I still believe that it is generalizable to the overall US population. This suggests that the epidemic of obesity in the US will have long term consequences on heart disease in this country," Dr. Bryg said.
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