Mar. 7, 2001 DALLAS, March 6, 2001 – Re-blocking of the artery – a common complication after angioplasty – is a more serious problem for people with diabetes than for non-diabetics, and could explain why they face an increased risk of death following the procedure, researchers report in today’s Circulation: Journal of the American Heart Association.
“Our study provides an explanation for the previous observation of the poor outcome of diabetic patients after coronary balloon angioplasty,” says Eric Van Belle, M.D., an assistant professor at the University of Lille, France, and lead author of the study. “It also suggests a new therapeutic target to improve the outcome of these patients.”
Compared to the general population, people with diabetes fare worse following balloon angioplasty, in which a catheter tipped with a deflated balloon is inserted into a narrowed artery and the balloon is inflated to push open the clogged area and dilate the blood vessel. Van Belle says his study indicates that diabetics should be treated differently from the general population and may lead to new therapies to target re-blocking, or restenosis, in that group.
“This suggests that balloon angioplasty alone must be abandoned in diabetic patients,” he says. “For this group of patients, using a stent – a wire mesh tube implanted to prop open the artery – reduces the incidence of restenosis following balloon angioplasty, although it still is higher than in non-diabetics who receive stents.” In addition, Van Belle says stenting should be combined with powerful antiplatelet drugs for this high-risk group of patients.
The procedure, also known as percutaneous transluminal coronary angioplasty (PTCA), is a common alternative to bypass surgery for many patients. However, the increased death rate for diabetics – which is four to five times higher than for non-diabetics over five years – has led to questions about whether diabetics should undergo PCTA.
The study has great public health significance because diabetes accelerates the development of heart and blood vessel disease. While diabetics make up only about 5 percent of the general population, they account for 15 to 25 percent of the candidates for PTCA or coronary artery bypass graft surgery, Van Belle says.
More than 500 individuals with diabetes were followed for more than 6 ½ years. Van Belle’s team found that the amount of restenosis in the diabetics’ blood vessels six months after PTCA was associated with increased mortality – most notably in a subgroup of diabetic patients with complete restenosis, known as the “occlusive” form, he says.
“This is the first study to show that occlusive restenosis has a clinical relevance, and is one of the strongest predictors of mortality in the diabetic population, regardless of the usual risk factors like age, left ventricular ejection fraction, other diabetes-related complications, high blood pressure or coronary artery disease in multiple vessels,” he says.
Van Belle adds that the study raises intriguing questions about how restenosis could be so critical in diabetics as compared to non-diabetics.
In an accompanying editorial, Burton E. Sobel, M.D., Amidon Professor and Chair of the Department of Medicine, University of Vermont College of Medicine, Burlington, suggests that the high levels of insulin in diabetics blood may affect clotting, protein breakdown or the types of cells involved in the re-closure process.
Non-diabetics have robust re-growth of smooth muscle cells, he explains. In contrast, diabetic restenosis contains more lipids – the blood fats that figure in cholesterol levels – and non-cellular material that is more likely to rupture and cause heart attacks or strokes.
In his own practice, Van Belle brings diabetic patients back for a follow up angiography to check for re-blockage six months after PTCA. “It is critical in the management of diabetic patients for physicians to understand the reasons for their poor outcome after PTCA, such as why diabetic restenosis is different from the soft, fibrous tissue found in restenosis in non-diabetics,” adds Van Belle. “An answer to that question may help in designing new medications or other approaches to improve PTCA outcomes in this high-risk group.”
Co-authors include Régis Ketelers, M.D.; Christophe Bauters, M.D.; Marc Périé, M.D.; Kaveh Abolmaali, M.D.; Florence Richard, M.D., Ph.D.; Jean-Marc Lablanche, M.D.; Eugène P. McFadden, MRCPI; and Michel E. Bertrand, M.D.
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