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Blood Sugar Control Linked to Angioplasty or Stenting Success Rates

BETHESDA, MD — January 7, 2003 - Diabetic patients who undergo angioplasty or stent procedures to open blocked coronary arteries are less likely to suffer restenosis, need cardiac hospitalization, or have a recurrence of angina if they maintain strict blood sugar control, according to a study in the Jan. 7, 2004 issue of the Journal of the American College of Cardiology.

“All patients with diabetes should be managed to achieve adequate glycemic control. It is well established that tight glycemic control can reduce microvascular events, and as such, all efforts should be made to achieve tight glycemic control in these patients. This study adds additional information and an impetus for doing so by suggesting that tight control of blood sugar may improve outcomes in diabetic patients undergoing coronary interventional procedures,” said Roberto A. Corpus, MD, from the Mid America Heart Institute in Kansas City, Mo., who performed the study with colleagues at William Beaumont Hospital in Royal Oak, Mich.

Hemoglobin A1c is a glycated form of hemoglobin that results when red blood cells are exposed to high blood sugar levels. Measuring hemoglobin A1c provides an indication of what a patient’s average blood sugar levels have been over a period of about three months. This study used the American Diabetes Association guideline that defines “optimal” glycemic control as a hemoglobin A1c level at or below 7 percent.

It is well-known that chronically high blood sugar levels can lead to damage to the inner lining of blood vessels, augmentation of the inflammatory response, and accelerated cellular proliferation. Consequently, people with diabetes have a higher than normal risk of the development and progression of coronary artery disease. Diabetes is also linked to a several-fold higher likelihood that a treated coronary artery will become clogged again (restenosis).

“Despite this, few studies have examined the link between hyperglycemia (elevated blood sugar levels) and restenosis. While several landmark trials have shown that strict control of hyperglycemia can lower microvascular complications such as nephropathy, neuropathy, and retinopathy, data demonstrating benefit in terms of the general occurrence of macrovascular events (heart attack, stroke, etc.) have been inconclusive. This is one of the first studies to specifically look at the effect of tight glycemic control in diabetic patients undergoing coronary interventional procedures,” Dr. Corpus said.

The researchers studied 239 patients undergoing percutaneous coronary intervention (typically balloon angioplasty and/or stenting) to open clogged coronary arteries. Most of the participants (179) had diabetes. The remaining 60 patients without diabetes served as a control group. Each patient’s hemoglobin A1c level was measured at the time of the procedure. All of the diabetic patients included in the analysis had type 2 diabetes, also known as adult-onset diabetes.

Diabetic patients with tight glycemic control had a significantly lower rate of repeat revascularization within 12 months compared to diabetic patients with poorer blood sugar control (15 percent vs. 34 percent). Furthermore, the rate of repeat revascularization in well-controlled diabetic patients was similar to patients without diabetes (15 percent vs. 18 percent). Finally, well controlled diabetic patients had lower rates of cardiac re-hospitalization as well as recurrent angina at 12-month follow-up. The hemoglobin A1c level was an independent predictor of restenosis even when the researchers statistically adjusted their results to control for other factors, including other cardiovascular risk factors, laboratory parameters, and vessel characteristics.

Dr. Corpus said the results of this study could have important public health implications, given the epidemic proportions of diabetes.

“In diabetic patients, cardiovascular disease is the most significant cause of morbidity and mortality and as such, therapies directed at reducing cardiovascular risk in these patients are warranted. All patients with diabetes should be aggressively managed to achieve optimal glycemic control; that is, hemoglobin A1c at or below 7 percent. These data suggest that in diabetic patients, tight glycemic control may be beneficial in reducing the risk of restenosis and may improve clinical outcome following percutaneous coronary revascularization,” Dr. Corpus said.

In this study, hemoglobin A1c was measured just once, so further prospective studies are needed to determine if treatment that leads to lower hemoglobin A1c levels is beneficial. Furthermore, insulin use reached borderline significance as a predictor of restenosis, which Dr. Corpus said may suggest a role of insulin in the restenotic process or may simply indicate a worsened degree of the diabetic state and as such imply a significantly increased burden of disease and thus poorer outcome.

In an editorial in the journal, Ran Kornowski, MD, FACC and Shmuel Fuchs, MD, with the Rabin Medical Center in Petach-Tikva, Israel, pointed out that 30 to 40 percent of patients who have restenosis have diabetes, so reducing the rate among these patients would have a major favorable impact on overall outcomes of angioplasty and stenting.

“The current study underscores the potential significance of an ‘aggressive’ metabolic normalization approach as part of a comprehensive therapeutic strategy aimed at inhibiting atherosclerotic progression and preventing restenosis among diabetic patients. This approach should be evaluated in a large cohort of patients wherein several preprocedural aggressive metabolic modification strategies should be examined,” Drs. Kornowski and Fuchs wrote.

The editorial authors pointed out important issues need further study, such as just how strict blood sugar control needs to be to reduce restenosis rates and whether lowering blood sugar in patients undergoing angioplasty or stenting is practical and beneficial.

“Nonetheless, the importance of a long-term comprehensive therapeutic approach directed toward metabolic normalization should be emphasized, using optimal glycemic control, adequate lipid-lowering strategy, aggressive blood pressure management, and other risk-factor modification. Currently, those therapeutic means may reduce the risk of long-term microvascular and macrovascular complications among diabetic patients regardless of restenosis prevention,” the editorial stated.

View the study:

Source: American College of Cardiology

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