Beta-Blockers Improve Bypass Outcomes
DURHAM, N.C. -- Giving patients a class of drugs known as
beta-blockers prior to coronary artery bypass surgery improves
the outcome of the surgery, according to a study by researchers
from Duke University Medical Center, Louisiana State University
Health Sciences Center and the Society of Thoracic Surgeons
Furthermore, the researchers believe that all patients
scheduled to undergo bypass surgery -- except for those whose
hearts are severely weakened -- should receive these drugs
before surgery. Since only about 60 percent of bypass patients
currently receive beta-blockers before surgery, the researchers
believe that by working together, cardiologists and surgeons
can improve survival rates of their heart patients.
The team's findings are published in the May 1, 2002 issue
of the Journal of the American Medical Association.
By blocking the stimulatory effects of the hormones
epinephrine and norepinephrine -- the "fight-or-flight"
hormones -- beta-blockers reduce heart rate and blood pressure.
Beta-blockers have been used for 20 years for different
ailments. Cardiologists use them to help treat high blood
pressure, chest pain and heartbeat irregularities.
Randomized clinical trials have proven the effectiveness of
beta-blockers in improving outcomes for heart patients in
general, and for patients undergoing non-cardiac surgery.
However, little data exists on the effects of beta-blockers if
given to patients just before surgery.
"In our large observational analysis, we found a small but
important survival benefit for patients given beta-blockers
before bypass surgery," said Duke cardiologist Eric Peterson,
M.D., who along with co-investigator LSU heart surgeon T. Bruce
Ferguson, M.D., conducted the analysis. "This effect was seen
in all types of patients, and those patients who were the
sickest received the greatest benefit."
Specifically, patients receiving beta-blockers had a 30-day
mortality rate of 2.8 percent, compared to 3.4 percent for
those patients who did not. Furthermore, the researchers found
no negative side effects from the drug, except for those
patients whose heart pumps at 30 percent of its ability or
less. For that reason, these patients should not receive
beta-blockers, they said.
The timing of giving beta-blockers is not particularly
crucial, Peterson said. Patients who are on beta-blockers prior
to surgery would derive the protective benefit, while those not
taking the drug could receive it shortly before surgery.
"Early in my surgical training at Duke, we'd take patients
off beta-blockers for a while before surgery, and now we're
finding that they have a protective effect," Ferguson said.
"We've come full circle. These results should provide a
scientific basis for everyone involved in a patient's care to
make sure they receive beta-blockers before surgery."
In the past, it was believed that since beta-blockers
lowered heart rate and blood pressure, patients would be at
greater risk during surgery.
"While this study did not address the issue of the mechanism
of protection, it appears that beta-blockers ?soak up' or
neutralize the increased amount of stress hormones the body
secretes in response to the act of surgery," Peterson said.
For their analysis, Ferguson and Peterson consulted the
STS-coordinated National Adult Cardiac Surgery Database, which
had data on 629,877 patients who underwent bypass surgery at
497 hospitals in the U.S. and Canada between 1996 and 1999.
They compared the outcomes of patients who received
beta-blockers to those who didn't.
"From 1996 to 1999 we saw that the usage of beta-blockers
increased from 50 to 60 percent, and while that is an
improvement, there is still a long way to go," Peterson said.
"We also found a wide variation among hospitals, with usage
rates ranging from 20 to 85 percent."
The researchers view the findings of their analysis as an
opportunity to improve survival rates for an already successful
surgery, which is performed more than 570,000 times each year
in the United States.
"This is an issue to be addressed at all levels of a
patient's care -- heart patients who could benefit from
beta-blockers should be on them even before surgery, and we as
surgeons or anesthesiologists should make sure patients receive
them if they're not on them already," Ferguson said.
Additionally, the researchers found that patients taking
beta-blockers spent less time on mechanical ventilation after
surgery and experienced fewer instances of kidney problems.
The researchers point out that this study is an
observational analysis and that future randomized trials need
to be conducted to refine the findings and to better understand
the mechanism of protection.
"One of the most important aspects of this study is that it
was conducted with a huge national databank unique to cardiac
surgery in conjunction with the Duke Clinical Research
Institute, one of the leading research organizations," Ferguson
said. "The marriage of this unique database and the DCRI
creates opportunities to conduct future studies like this."
The analysis was supported by a grant to the Society of
Thoracic Surgeons from the Agency for Healthcare Research and