December 20, 2005

Insight into heart condition tied to athlete deaths

By Amy Norton

NEW YORK (Reuters Health) - A relatively rare heart
condition that has been linked to athletes' deaths can arise
anywhere from childhood to well into middle age, and its first
symptoms range from heart palpitations to sudden death, a new
study shows.

The study, according to researchers, gives the most
comprehensive overview to date of a fairly uncommon heart
defect called arrhythmogenic right ventricular dysplasia, or

Though the inherited disorder has been recognized for more
than 20 years -- and tied to the deaths of some young athletes
-- there has been surprisingly little research on it, Dr. Hugh
Calkins, the senior author on the study, told Reuters Health.

To help fill the gap, he and his colleagues at the Johns
Hopkins University School of Medicine in Baltimore gathered
data on 100 adults and children diagnosed with ARVD. The
patients, whose average age was 29, were part of an ARVD
registry begun at Johns Hopkins in 1998.

About one-third of subjects were diagnosed with the heart
condition at autopsy, after they died suddenly of cardiac
arrest. The rest were diagnosed after warning signs like an
abnormally rapid heartbeat or fainting spells, according to
findings published online by Circulation, an American Heart
Association journal.

Estimated to affect about 1 in 5,000 people, ARVD involves
a defect in proteins that link muscle cells in the heart. Over
time, muscle in the heart's right ventricle -- one of its
pumping chambers -- is replaced by fat and scar tissue, which
causes abnormal, sometimes fatal heart rhythms.

People inherit a predisposition toward this "abnormal glue"
between heart cells, Calkins explained, though they do not
necessarily develop ARVD.

One of the factors that appears key in whether a person
develops heart rhythm disturbances is exercise; ARVD is a cause
of sudden cardiac death in athletes, and when people are known
to have a predisposition to the disease they are advised to cut
out exercise, Calkins said.

Researchers speculate that when heart muscle cells already
have trouble sticking together, the stress of exercise may
damage the cells and lead to the scarring and abnormal heart
rhythms that mark ARVD.

Among the patients Calkins and his colleagues followed, 31
were diagnosed with ARVD only at autopsy. Their average age was
29, though they ranged in age from 13 to 70.

While most died suddenly without prior symptoms of the
heart defect, eight did have warning signs before their deaths
-- most commonly passing out on at least one occasion.

This underscores the importance of having a medical
evaluation after a fainting episode, according to Calkins.

Indeed, the study found, of the 69 patients who were
diagnosed with ARVD while still alive, fainting and heart
palpitations were the most common symptoms that brought them to
the doctor. Diagnosis of the disease relies on a battery of
cardiac tests, including electrocardiograms and
echocardiograms; these same tests can be used to screen
first-degree relatives of people with ARVD.

The use of multiple tests is vital, Calkins said, as no
single one can pinpoint the disease.

The "good news" from the study, according to the
researchers, was that patients who were diagnosed after ARVD
warning signs fared well. Over about 6 years of follow-up,
three of the 69 died, and none of the 47 who were treated with
an implanted defibrillator died of cardiac arrest.

The devices, which automatically detect a heart rhythm
disturbance and deliver an electric shock to restore a normal
pattern, are widely used in the U.S. This, according to Calkins
and his colleagues, largely accounts for the "excellent
prognosis" after ARVD is diagnosed.

SOURCE: Circulation, online December 12, 2005.