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HONOLULU. -- Coronary artery bypass patients are twice as
likely to suffer a later major cardiac event if they experience
abnormalities in the motion of the walls of the main pumping
chamber of their heart during surgery, according to Duke
University Medical Center researchers. According to the
researchers, their findings suggest that such patients should
be followed closely after discharge.

Using transesophageal echocardiography (TEE), which provides
high-quality images of the heart, the researchers correlated
abnormal movements in the walls of the left ventricle during
surgery with subsequent heart attacks, death or the need for
another bypass surgery or angioplasty procedure within two
years.

The researchers said that the findings of their analysis can
help physicians predict which of their bypass patients are at
the higher risk of adverse outcomes after surgery. They also
said the findings further confirm the utility of using TEE
during surgery, an approach that is routine at Duke University
Hospital and is becoming the standard of care nationally.

"One small study in 1989 demonstrated that abnormal wall
motion seen by intraoperative TEE was predictive of adverse
outcomes for patients while still in the hospital," said Duke
cardiothoracic anesthesiology fellow Daniel DeMeyts, M.D., who
presented the results of the Duke study April 27, 2004, at the
annual scientific session of the Society of Cardiovascular
Anesthesiologists.

"Ours was the first large-scale study to examine whether or
not new wall motion abnormalities detected during surgery were
predictive of long-term outcomes," DeMeyts continued. "The
results of our analysis do clearly show that the presence of
new abnormal movements in the walls of the left ventricle put
bypass patients at a higher risk of future adverse
outcomes."

During a TEE examination, a small probe is placed down the
esophagus to a location behind the heart. From this vantage
point, it captures moving images of the heart -- and especially
the left ventricle. It has been used routinely as a diagnostic
tool to assess valve function and areas of heart muscle that
have been damaged or killed by past heart attacks.

The routine use of TEE during bypass surgery is gaining
wider acceptance, the researchers said.

Physicians at Duke have employed TEE on all bypass
procedures performed since the early 1990s. For their analysis,
the researchers identified 1,543 bypass patients who underwent
bypass surgery since 2000, of which 221 suffered a major
cardiac event within two years.

For each patient, the researchers studied 16 distinct areas
of the muscle wall of the left ventricle. For each area, the
movement of the wall was given one of four scores: normal (1)
and three degrees of abnormal, weak movement (2), no movement
(3) or erratic movement (4). The individual scores for each
region were added together and then divided by 16 to yield a
composite score.

"We found that there was a significant statistical
association between the higher post-bypass scores and the
occurrence of adverse events," DeMeyts said. "As the score
increased, so did the risk even after accounting for other risk
factors such as age and diabetes."

Both DeMeyts and senior member of the research team, Joseph
Mathew, M.D. said that while there is not an immediate clinical
application of the new findings, the occurrence of wall motion
abnormalities during surgery should spur physicians to follow
these patients more closely after discharge. Most of these
patients will be treated aggressively, and will be prescribed
drugs, such a beta blockers, which are known to have a
protective benefit.

A key question to be answered, they continued, is what
causes the wall motion abnormalities. They could be the result
of the existing heart disease, the time the heart is stopped to
allow the surgery to occur, the actual surgery itself, or a
combination of factors.

"The main problem is that we don't have the technology to
adequately measure the patency of the grafted arteries while
we're in the operating room," Mathew said. "When we have that
we can really make a difference by identifying any problems in
the operating room and fixing them. The current technologies
are fine at imaging blood flow in the larger vessels, but no
technique is good at looking at blood flow in the smaller
vessels."

The researchers are currently investigating another
ultrasound technique using TEE that may allow them to evaluate
small vessel blood flow before the patient leaves the operating
room.

While the current study used aggregate scores from the 16
different regions of the left ventricle, the researchers are
now focusing on dividing the left ventricle into three regions
based on supply from the three main coronary arteries to see if
the abnormal wall motions in specific regions confer more risk
than other areas. They are also studying the effects of these
new wall motion abnormalities on length of hospitalization.

The analysis was supported by Duke's Department of
Anesthesiology.

Other members of the Duke team were Madhav Swaminathan,
M.D., Mihai Podgoreanu, M.D., John Booth, M.D., Richard Morris,
Ph.D., Fiona Clements, M.D., Hilary Grocott, M.D., and Mark
Newman, M.D.