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ECG Transmission from Ambulance Cuts Time to Direct Clot Removal

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Duke Health News 919-660-1306

DURHAM, N.C. -- When emergency medical technicians (EMTs)
wirelessly transmit eletrocardiograms (ECG) directly to a
cardiologist's hand-held device, heart attack patients can
potentially receive direct clot removal in half the usual time,
according to cardiologists at Duke University Medical Center
and NorthEast Medical Center, Concord, N.C.

Cutting this "door-to-reperfusion" time is critical, the
cardiologists said, because the sooner a patient suffering from
a heart attack receives an artery-opening procedure, the more
likely heart muscle can be saved, and that the patient will
potentially derive a survival benefit.

While the American College of Cardiology (ACC) and the
American Heart Association recommend that patients have their
arteries opened directly within 90 minutes of arriving at the
hospital – the NorthEast Medical Center team was able to cut
that time to 50 minutes. The national average
"door-to-reperfusion" is about 100 minutes, the researchers
said.

The results of the pilot project were presented March 13,
2006, by Duke Clinical
Research Institute
cardiology fellow George Adams, M.D.,
during the 55th annual scientific sessions of the ACC in
Atlanta. His study is one of five finalists for an ACC Young
Investigator Award.

The team achieved this significant time savings by directly
linking EMTs with cardiologists and bypassing the hospital's
emergency department for the small proportion of those patients
with chest pain whose ECG is distinctly diagnostic. In the
current study, specially trained EMTs transmitted ECG tracings
electronically from the scene or in the ambulance to an on-call
cardiologist's personal digital assistant (PDA). The
cardiologist -- on spotting the definitive signs of a heart
attack -- could mobilize the catheterization laboratory while
the patient was en route to the hospital.

While the time savings achieved in the current pilot project
are significant, the researchers point out that the results
will need to replicated in more diverse settings. In the
current project, NorthEast is staffed by a small number of
interventional cardiologists at one hospital with one ambulance
service. Duke researchers are currently organizing a 12-site
study across the U.S. in larger and smaller cities with
different sized hospitals and ambulance services.

"We found that the pre-hospital wireless transmission of an
ECG directly to a cardiologist's hand-device significantly
reduced the time from emergency room door to reperfusion,"
Adams said. "When the cardiologist can directly see an ECG, it
clarifies the decision to mobilize all the personnel necessary
for the cath lab to be ready to go when the patient
arrives."

The researchers were studying a specific kind of heart
attack known as an ST-segment elevation myocardial infarction
(STEMI). When a cardiologist spots a major elevation of the
tracing in the ST portion of an ECG study, there is little
question that patient is having a heart attack, Adams said.

In the final two years of the four-year pilot project, the
team enrolled patients with a suspected STEMI who were taken to
NorthEast Medical Center. During the intervention phase of
trial, the team enrolled 101 self-transported patients, and 24
ambulance patients where the wireless ECG transmission was
successful, and 19 patients for whom the wireless transmission
was unsuccessful.

"The median 'door-to-reperfusion' time for those with a
successful transmission was 50 minutes, significantly faster
than the 96 minutes for those who transported themselves and
the 78 minutes for those whose transmission failed," Adams
said.

Key to the success of the project, the researchers said, is
the training of the EMTs. Currently, almost all ambulance
services are equipped to perform an ECG at the scene or in the
ambulance. However, for any such project to be successful, the
researchers said, an EMT needs to be able to spot tell-tale
abnormalities, since only about five percent of patients
experiencing chest pains need an immediate catheterization.

"Wireless ECG transmission gets at the 'heart' of the
problem, which is communication." said Duke cardiologist Galen
Wagner, M.D., senior member of the research team. "We have
ability to transport patients and we are good at clearing clots
from arteries – the challenge is to remove the barriers in
between."

Also importantly, said the researchers, the findings add
further evidence that patients or families should always call
for an ambulance instead of driving themselves to a hospital if
a heart attack is suspected. While it may seem intuitive that a
patient could get themselves to a hospital sooner, they will
typically have to go through the emergency room triage system
before actually going to the catheterization lab, if
appropriate, noted the researchers.

Interestingly, as the project became known to Cabarrus
County residents over the four-year period, the researchers
noticed a decline in the number of potential heart attack
patients transporting themselves to the hospital.

While the upcoming trial will test wireless transmission
capabilities in a number of different settings, it will also
study the effects of shortening the "door-to-reperfusion" time
on mortality and heart muscle salvage. It is estimated that
more than 500,000 Americans will come to a hospital with an
STEMI.

The pilot project was supported by the William T. Morris
Foundation, N.Y., the Duke Endowment, Charlotte, N.C., and
Welch Allyn, Skaneateles Falls, N.Y., which provided some of
the equipment. The investigators have no financial interest in
Welch Allyn.

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