Voice of the Diabetic

Voice of the Diabetic

Back|

Next|

Table of Contents|

Home

CARDIOVASCULAR HEALTH: BYPASS MAY BE

BETTER FOR DIABETICS

Individuals with severe coronary artery disease face

the risk of vascular blockage, which can lead to angina, weakness, and heart

attack. Traditionally, these folks have received one of two treatments: CABG

(bypass surgery) or PTCA (percutaneous transluminal coronary angioplasty, "balloon

angioplasty"). Diabetes is a major cause of heart disease, and enough diabetics

have undergone one or the other procedure to form a statistical picture of these

procedures' effectiveness.

PTCA uses a catheter, which is inserted into the obstructed vessel from an

entry point in the groin, and inflates like a balloon, to dilate the blocked

vessel at the point of obstruction, allowing blood to flow past the blockage.

CABG, a major operation, involves opening the chest and providing a new channel,

or "bypass," for the blood to flow. Both treatments alleviate the effects of

coronary artery disease, but neither alters the natural course of the disease.

One might expect the "success" rates of the two procedures to be about the

same, or for the less invasive, PTCA, to be better. Beginning in August 1988,

the Bypass Angioplasty Revascularization Investigation (BARI), a major study

sponsored by the National Heart, Lung, and Blood Institute, part of the National

Institutes of Health, compared the effectiveness of the two procedures. Results

were surprising.

Using "mortality after five years of follow up" as a yardstick, the BARI study

found that for non diabetic patients, both procedures scored equally, with a

9% mortality rate. For diabetics on insulin or oral hypoglycemics (type 1 or

type 2), the five year mortality rate following PTCA, the less invasive procedure,

was 35%, and the rate for CABG, bypass surgery, was 19%. Although the higher

overall mortality rate from diabetic heart disease was not unexpected, the excess

mortality with balloon angioplasty had not been anticipated.

Results of the study indicate that bypass surgery should be the preferred treatment

for diabetic patients on insulin or oral medications, who have multi vessel

coronary artery disease and need a "first coronary revascularization" (first

time PTCA or CABG). As the Centers for Disease Control reports that, in 1989,

about 48% of all diabetes related deaths had major cardiovascular disease as

the underlying factor, these findings are expected to have major impact. Patients

were eligible for the BARI trial if they had coronary artery disease with a

50% or more luminal obstruction (as measured by calipers) in at least two of

the coronary vessels supplying two or three major coronary territories. They

had to have clinically severe ischemia (measurable obstruction to blood flow),

and no prior revascularization.

Patients were ineligible, if, for example, they had insufficient angina or

ischemia, required emergency revascularization, had left main stenosis of 50%

or greater, had a noncardiac illness expected to result in limited survival,

primary coronary spasm, or a poor quality angiogram (x ray examination of the

circulatory system). All patients accepted for the test received "risk factor

modification": help with smoking cessation, appropriate exercise, and diet.

Findings of the BARI study were reviewed on September 13, 1995, by the Data

and Safety Monitoring Board, a panel of PTCA experts, cardiovascular surgeons,

clinical cardiologists, biostatistics experts and ethics specialists. The board

concluded that the differential results of the two treatments, and the unfavorable

mortality for diabetics on insulin or oral hypoglycemics, were unlikely to be

due to chance. The board recommended to the National institutes of Health that

physicians, other health professionals, and the public be promptly informed

of the results. On September 21, 1995, the NIH issued a Clinical Alert to Physicians,

highlighting the study s findings and recommending appropriate changes in treatment

for diabetic patients who present with severe heart disease.

In March, 2000, Researchers from Duke University Clinical Research Institute

reported that in spite of the NIH s Clinical Alert, many cardiologists were

continuing as before, using angioplasty, stents, and glycoprotein platelet inhibitors,

instead of bypass surgery, in spite of the total lack of evidence that these

techniques improve outcomes sufficient to overturn the results of the BARI study.

The Duke study found that while surgeons wholeheartedly embraced the results

of the study, cardiologists (who the patient sees first) were not referring

their diabetic patients on to the surgeons!

In summary: The BARI study was a careful comparison of the results of two medical

procedures frequently used in response to multiple coronary artery disease.

Many "endpoints" were investigated, including: Patients' anginal status, number

of diseased vessels, functional status, quality of life, gender, age, race,

and presence/absence of diabetes. Although the study considered many issues,

its findings for diabetics were particularly significant. The study strongly

suggests that if you are diabetic, using insulin or oral hypoglycemic agents

(sulfonylureas), and you suffer from multiple coronary artery disease, and if

you are at the point of needing a first revascularization, evidence strongly

suggests you will fare better with CABG, bypass surgery, than with PTCA, balloon

angioplasty, as an initial treatment. If you have diabetes, and need such treatment,

discuss your options, and the BARI study, with your doctor, and, if necessary,

seek a second opinion.

Anyone who has evidence of coronary artery disease, with or without a prior

PTCA or CABG, needs, under close physician monitoring, to aggressively reduce

known risk factors, such as smoking cessation, appropriate control of blood

pressure and serum cholesterol, and needs to achieve optimal control of their

diabetes.

From the Editor: I've had bypass surgery. Several doctors have told me the

best way to determine if you have coronary artery disease is with a "routine

exercise treadmill test." While you work out, electrical instruments measure

your heart rate, heart rhythm, EKG, and blood pressure, and the doctor will

note any other symptom you may have. Added together, all the test data give

a good picture of the state of your heart.

You can have a normal pulse, and significant coronary artery disease. Diabetics

(and non diabetics) can have normal EKGs, too, even in the early stages of a

heart attack. One physician told me: "The absence of electrocardiographic abnormalities

does not preclude the presence of significant heart disease."

My doctors said that if you have multiple risk factors, like cholesterol, hypertension,

smoking, cardiac arrhythmia ("heart murmur"), or a family history of heart trouble

(another is the presence of diabetes), you ought to have periodic treadmill

checks, to see how your heart is doing. If you've had diabetes for 20 years

(IDDM or NIDDM) you could benefit from this test. If heart disease is discovered

soon enough, medical intervention can make a difference.

Back to Top