Study Pinpoints Atrial Fibrillation Risk at 40
Percent for Those with Diabetes, Maybe Higher
Nearly nine in 100 people over age 80 - have atrial
fibrillation; risk rises by 3% for each additional year patients have
diabetes – watch video
April 23, 2010 - As the U.S. population keeps aging
and gaining weight, diabetes is becoming increasingly common. Research
has associated diabetes with many additional ailments, including the
most common type of irregular heartbeat – atrial fibrillation, which if
a problem for millions of senior citizens. This heart problem can
increase the risk of stroke and death. A new study pinpoints this risk
at 40 percent, and even higher with lesser blood sugar control.
Earlier studies of diabetes and atrial fibrillation
have conflicted. Now in the Journal of General Internal Medicine
Dr. Sascha Dublin of Group Health Research Institute clarified the risk
level.
For three years, Dr. Dublin and her colleagues
tracked more than 1,400
Group Health patients who had newly recognized atrial fibrillation.
They compared these “cases” with more than 2,200 “controls.” The
controls were matched to the cases by age, sex, year, and whether they
were treated for high blood pressure; but unlike the cases, they had no
atrial fibrillation.
Dr. Dublin’s study was the first to examine the
relationship between atrial fibrillation and the duration of patients’
diabetes and their blood sugar levels. Unlike most prior studies, this
one also adjusted for patients’ weight, which is important because both
diabetes and atrial fibrillation are more common in heavier people. Here
is what she found:
● Patients with diabetes were 40 percent more
likely to be diagnosed with atrial fibrillation than were people without
diabetes.
● The risk of atrial fibrillation rose by 3
percent for each additional year that patients had diabetes.
● For patients with high blood sugar (glycosylated
hemoglobin, also known as HBA1c more than 9 percent), the risk of atrial
fibrillation was twice that for people without diabetes.
● But patients with well-controlled diabetes
(HBA1c 7 percent or less) were about equally likely to have atrial
fibrillation as people without diabetes.
“When a patient with diabetes has symptoms like
heart palpitations, clinicians should have a higher level of suspicion
that the reason could be atrial fibrillation,” Dr. Dublin said.
“This heart rhythm disturbance is important to
diagnose, because it can be treated with medications like warfarin that
can prevent many of the strokes that the atrial fibrillation would
otherwise cause.”
It is hard to establish which comes first -
diabetes or atrial fibrillation - with this kind of case-control study,
unlike a randomized trial, Dr. Dublin said. “But our finding that the
risk of atrial fibrillation is higher with longer time since patients
started medications for diabetes, and with higher blood glucose levels,
is strongly suggestive that diabetes can cause atrial fibrillation.”
She used time since starting diabetes medication as
a measure of how long patients had the disease.
About one in 100 people - and nearly nine in 100
people over age 80 - have atrial fibrillation, according to Dr.
Heckbert, a professor of epidemiology and scientific investigator in the
Cardiovascular Health Research Unit at the University of Washington (UW)
and an affiliate investigator at Group Health Research Institute.
In many cases, atrial fibrillation has no symptoms,
and it is not necessarily life threatening. But it can cause
palpitations, fainting, fatigue, or congestive heart failure. Atrial
fibrillation can also make blood pool—and sometimes clot—in the atria.
When parts of clots break off and leave the atria, they can lead to
embolic strokes, as happens in more than 70,000 Americans a year.
Dr. Dublin’s work was funded through a Veterans’
Affairs Health Services Research & Development fellowship and a Paul
Beeson Career Development Award from the National Institute on Aging.
The Beeson Award is also supported in part by the American Federation
for Aging Research, the Hartford Foundation, the Atlantic Philanthropies
and the Starr Foundation. The National Heart, Lung, and Blood Institute
funds the Heart and Vascular Health Study, which collects data on Group
Health patients newly diagnosed with atrial fibrillation and other
cardiovascular conditions.
The study of atrial fibrillation, led by Dr.
Dublin’s co-author Dr. Susan Heckbert, aims to find new factors that
raise the risk of developing this quivering of the heart’s upper
chambers (atria).
Other co-authors were Group Health Research Institute Senior
Investigator
Bruce M. Psaty, MD, PhD, who co-directs the
UW’s Cardiovascular Health Research Unit; and Nicole L. Glazer, PhD,
Thomas Lumley, PhD, Kerri L. Wiggins, MS, RD, of the UW; Nicholas L.
Smith, PhD, of the UW and Veterans Affairs Puget Sound Health Care
System; and Richard L. Page, MD, of the University of Wisconsin School
of Medicine and Public Health in Madison.
