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ACC – Amanda Jekowsky: (202) 375-6645,
ajekowsk@acc.org
November
9, 2009
Size Matters: Obesity Leading Risk Factor of Left Atrial Enlargement
During Aging
Aside from aging itself, obesity appears to be the most powerful
predictor of left atrial enlargement (LAE), upping one’s
risk of atrial fibrillation (the most common type of arrhythmia),
stroke and death, according to findings published in the November
17, 2009, issue of the Journal of the American College
of Cardiology.
This prospective study—the first to evaluate factors
affecting left atrial remodeling during aging over 10 years—found
obesity and hypertension to be independent predictors of LAE,
both resulting in a variety of structural and functional changes
in the heart. The highest measures of left atrial volume (iLA)
were seen in obese patients with high blood pressure; this
group also had the greatest increase in iLA (+6ml/m) and the
highest incidence of LAE upon follow-up (31.6 percent compared
to baseline prevalence of 10 percent among all participants).
In linear regression models, the effect of obesity was almost
twice that of hypertension.
Results of the present study also suggest that LAE in obese
and hypertensive patients may be caused by different physiological
mechanisms. In individuals with high blood pressure, the heart
has to deal with greater pressure, which results in a thickening
of the walls of the left ventricle. This change also affects
the left atrium as the pressure in this chamber ultimately
increases as well as resulting in enlargement and loss of
function of the atrium. The mechanisms by which obesity might
promote the increased size of the left atrium are seemingly
more complex than with hypertension. Obese subjects may undergo
dilatation of this chamber because of the cardiac output;
that is, the blood that is transported by the heart every
minute is increased. Subsequently, these alterations may lead
to a volume overload in the left atrium.
The present data further confirm the strong relation of obesity
and LAE reported in previous studies, some of which have shown
that excess weight appears to impact left atrial size even
at a very early age, potentially predisposing young obese
individuals to future cardiovascular problems. Amid the growing
obesity epidemic, authors stress the importance of early assessment
and intervention, especially in younger obese patients to
prevent the premature onset of cardiac remodeling—changes
in size, shape, and function of the heart—resulting
from LAE. Authors caution that the extent to which weight
management or moderate weight loss can improve LAE remains
unclear and needs further investigation.
Study participants included 1,212 men and women aged 25 to
74 years old who were followed between October 1994 and June
1995. Baseline data were obtained from a survey of the population-based
Monitoring of Trends and Determinations in cardiovascular
Disease (MONICA) study in Germany. Left atrial volume was
determined by an echocardiogram at baseline and again after
10 years. All participants underwent blood pressure screening
and an interview related to personal medical history, lifestyle
and health behavior. Obesity was defined as body mass index
(BMI) = 27.3 kg/m2 in men and 27.8 kg/m2 in women.
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About the ACC:
The American College of Cardiology is leading the way to optimal
cardiovascular care and disease prevention. The College is
a 37,000-member nonprofit medical society and bestows the
credential Fellow of the American College of Cardiology upon
physicians who meet its stringent qualifications. The College
is a leader in the formulation of health policy, standards
and guidelines, and is a staunch supporter of cardiovascular
research. The ACC provides professional education and operates
national registries for the measurement and improvement of
quality care. More information about the association is available
online at www.acc.org .
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