Bypass best for people with diabetes

Surgery beats stenting if you have diabetes and heart disease, too.

Both bypass surgery and its less invasive alternative, angioplasty plus stenting, are used to open severely narrowed coronary arteries. For most people, the two procedures have the same long-term benefits and risks. In people with diabetes, though, a new trial suggests that bypass surgery may be better than angioplasty plus stenting: it led to lower rates of heart attack and death over the next five years.

In angioplasty, artery-blocking deposits of cholesterol-filled plaque are pushed aside with a balloon. A small metal cylinder, or stent, is left behind to hold the vessel open. The balloon and stent are maneuvered into the heart through an artery in the groin. In bypass surgery, which requires opening the chest, a surgeon uses spare blood vessels to reroute blood around the blockages.

The results of the trial—Future Revascularization Evaluation in People with Diabetes Mellitus (FREEDOM)—were published in the New England Journal of Medicine on Nov. 6, 2012. It's considered one of the most important clinical trials of last year and sheds light on a longstanding controversy about which procedure is better for treating people with diabetes who have severely blocked coronary arteries.

"This finding is really quite important, since the opposite strategy is used more often right now, because angioplasty is less painful and seems more convenient," says cardiologist Dr. Thomas Lee, co-editor in chief of the Harvard Heart Letter.

The decision to perform angioplasty is often made while performing a diagnostic procedure known as cardiac catheterization. It's often convenient for the specialists performing the catheterization to think, "As long as we are here, let's fix this now," rather than stepping back and delaying the decision while bypass surgery is considered.

"At the very least, everyone should pause a second and consider whether the long-term outlook might be improved more with surgery than with angioplasty," says Dr. Lee.

About diabetes damage

Diabetes is on the rise in the United States. According to the Centers for Disease Control and Prevention, between 1995 and 2010 the incidence of diabetes increased by at least 50% in 42 states and 100% or more in 18 states. Further, people with diabetes are more likely than those without diabetes to develop coronary artery disease. Currently, one-fourth of all individuals with heart disease who undergo cardiac catheterization and angiography to diagnose narrowings in the arteries have diabetes.

People with diabetes also often have multiple risk factors, such as high blood pressure, elevated cholesterol, or obesity, and they may suffer damage to their blood vessels from high levels of sugar in the blood. Injured vessels attract cells that invade the vessel wall and promote inflammation, as well as the development of plaques (atherosclerosis).

Careful attention to risk factors—lowering blood sugar and cholesterol levels, maintaining an optimal weight, exercising, and not smoking, for example—often helps keep plaque in check. But not always. When a significant narrowing occurs, an individual may experience symptoms such as chest discomfort or shortness of breath. However, research shows people with diabetes are less likely to have such symptoms and more likely to have a heart attack, even from vessels with less plaque.

Comparing the procedures

For a long time, a case has been building that in people with diabetes, surgery may cause more short-term pain but greater long-term gain, compared with angioplasty. A study in the mid-1990s determined that people with diabetes and severe atherosclerosis did better after bypass surgery than after stenting. But because of significant advances in stent technologies and medications that have occurred since that time, many people choose the less-invasive procedure. However, the FREEDOM trial showed that bypass surgery may result in a 5.4% lower death rate and 7.9% lower heart attack rate than stenting—albeit with a 2.8% higher risk of stroke. This suggests that among people with diabetes, although angioplasty plus stenting may be more convenient and immediately easier on the body, bypass surgery may pay off in the long run.