NEW ORLEANS -- In contrast to the findings of a recent, highly publicized
clinical trial and subsequent federal recommendation, two Duke University
Medical Center studies suggest that diabetics with severe coronary artery
disease do equally well if they receive either angioplasty or coronary artery
bypass surgery.
While diabetics with multi-vessel disease tend to have slightly worse outcomes
with both treatments when compared with non-diabetics with similar disease,
the Duke researchers recommend that cardiologists not use diabetes as the
main factor when considering which procedure is best for their patients.
The Duke studies were prepared for presentation Tuesday (Nov. 12) at the
annual scientific meeting of the American Heart Association.
In July, investigators for a multi-center trial called BARI for Bypass Angioplasty
Revascularization Investigation reported in the New England Journal of Medicine
that the five-year survival for diabetics treated with bypass surgery was
80.6 percent, compared to 65.5 percent for diabetics treated with angioplasty.
Shortly before the overall BARI results were published, the National Heart
Lung Blood Institute recommended that diabetics with multi-vessel disease
be treated with bypass surgery.
After the BARI results were published, Duke researchers conducted their
own retrospective studies to see if the BARI results could be substantiated.
While they acknowledge that their studies are retrospective, the researchers
say the Duke studies provide more data that can be used in further discussion
of the issue.
The studies were supported by, and drew upon the expertise of, the Duke
Clinical Research Institute, which has been collecting and analyzing patient
data relating to heart disease since 1969.
"Our long-term data show that a history of diabetes holds a similar
risk for both angioplasty and bypass patients," said Dr. Greg Barsness,
Duke cardiology fellow. "Rather than using diabetes to determine the
revascularization choice, other factors should be considered, such as disease
severity and technical considerations."
Barsness's study followed 3,220 patients (769 of whom were diabetic) who
received either bypass or angioplasty at Duke between 1984 and 1990. After
five years (the same follow-up for the BARI trial), 74.3 percent of the
diabetics (vs. 86.3 percent for non-diabetics) who received bypass were
alive, while 76.4 percent of diabetics (vs. 88.3 percent of non-diabetics)
receiving angioplasty were alive.
"After adjusting for such factors as age, gender and characteristics
of their heart disease, we found that diabetics receiving either angioplasty
or bypass had lower survival than non-diabetics receiving these interventions,"
Barsness said. "However, in contrast to the results seen in the BARI
trial, the decrease in survival was similar among both angioplasty- and
bypass-treated diabetics."
For the second study, Dr. David Anderson, Duke cardiology fellow, pooled
data from seven recent multi-center trials involving 6,338 patients who
underwent angioplasty, 1,230 of whom were diabetics. Patients were followed
for nine months after their procedures.
"At least for the short term, our study suggests that factors other
than diabetes are more predictive of major adverse events after angioplasty,"
Anderson said. "Statistical analysis showed that while diabetics had
slightly more revascularization during a nine-month follow-up period due
to higher restenosis (where the artery closes again), other outcomes (death
and heart attack) are best predicted by the number of diseased vessels feeding
the heart, prior history of heart attack, and the degree of vessel blockage
before the procedure."
Physicians still do not understand why diabetics tend to do worse than non-diabetics.
While researchers have demonstrated that "tight" control of a
diabetic's glucose levels significantly delays the disease's destructive
effects on tiny blood vessels -- such as those in the eyes, extremities
and kidneys -- they still do not know how the disease effects the body's
larger blood vessels, like those supplying oxygen-rich blood to the heart.