Lower Blood Pressure Decreases Heart Attack Risk in Diabetics With Clogged Leg Arteries

February 2003 Lowering blood pressure can reduce heart attacks and other cardiovascular events in people with diabetes who also have clogged leg arteries, according to a study in todays rapid access issue of Circulation: Journal of the American Heart Association.

Peripheral arterial disease (PAD) is a manifestation of generalized atherosclerosis and, therefore, an independent predictor of cardiovascular events such as heart attack or stroke, says William R. Hiatt, M.D., senior author of the report and a professor at the University of Colorado Health Sciences Center in Denver. In PAD, fatty deposits build up along artery walls and reduce blood circulation, mainly in arteries leading to the legs and feet. Key risk factors for PAD include diabetes and high blood pressure.

"Despite the enormous prevalence and well-established risk of events, PAD is both unrecognized and undertreated by primary care physicians compared with the treatment of patients with coronary artery disease," Hiatt says.

In the Appropriate Blood Pressure Control in Diabetes (ABCD) study, researchers followed 950 people with type 2 diabetes (also called adult-onset diabetes) for five years. At the beginning of the study, 480 had normal blood pressure, and 53 had PAD. Participants were split into two groups.

Patients in the moderate treatment group took a placebo and had average blood pressure of 137/81 millimeters of mercury (mm Hg) during the last four years of the study. Those assigned to the intensive treatment group took the blood pressure-lowering medicines enalapril (an ACE inhibitor) or nisoldipine (a calcium-channel blocker) and had an average blood pressure of 128/75 mm Hg. The American Heart Association recommends that blood pressure for people with diabetes should be lower than 130/80 mm Hg.

There were 22 PAD patients in the intensive treatment group and 31 in the moderate treatment group. In patients with PAD, 12 cardiovascular events (38.7 percent) occurred among those on moderate treatment compared with three events (13.6 percent) on intensive treatment.

Researchers also measured patients" ankle brachial index (ABI), which is an indication of blood flow in the leg. ABI between 0.90 and 1.30 is normal, while ABI below 0.90 is characteristic of PAD. In a further look at PAD patients in the moderate treatment group, participants with low ABI had an increased risk of cardiovascular events. However, among PAD patients in the intensive treatment group, even patients with the lowest ABI were protected and had no clinically relevant increased risk of events, Hiatt says. He adds that the protective effect of intensive blood pressure control was not related to the type of blood pressure-lowering drug.

"Although high blood pressure is a major risk factor for PAD, to date, no prospective studies have been performed to assess whether intensive blood pressure control improves cardiovascular outcomes in patients with PAD," Hiatt says. "In the ABCD study, intensive blood pressure lowering was effective in reducing the risk of cardiovascular events in PAD patients using either a calcium-channel blocker or an ACE inhibitor."

He says these results are consistent with the emerging theme that aggressive blood pressure control is especially advantageous in the diabetic population. According to the American Heart Association, PAD affects 8 to 12 million Americans. About 50 million Americans over age 6 have high blood pressure.

Co-authors are Philip S. Mehler, M.D., (lead author); Joseph R. Coll, Ph.D.; Raymond Estacio, M.D.; Anne Esler, PhD.; and Robert W. Schrier, M.D.

This study was supported in part by the National Institute of Diabetes and Digestive and Kidney Diseases, a division of the National Institutes of Health.

Source: University of Colorado