Drugs called statins and ACE inhibitors can save those patients' lives, or their limbs, if they take the medications before having a leg bypass operation, the study finds.
But the U-M researchers found that only about half of patients whose leg vessel disease has progressed far enough to require a bypass operation are actually taking the potentially beneficial drugs.
The results, published in the February issue of the Journal of Vascular Surgery, suggest that vascular surgeons should make sure their patients are receiving appropriate drugs before performing leg bypass surgery to re-route blood flow around a severely clogged leg artery.
"What we found surprised us," says lead author and U-M vascular surgeon Peter Henke, M.D. "Patients who were taking statins before their leg bypass operation had better patency, or openness, of their bypass graft, and a lower risk of leg amputation after surgery. Those taking ACE inhibitors had a lower risk of dying after the operation. And the effect of the medications far outweighed the effects of the patients' PAD severity, other medical problems, or the type of graft used."
An estimated 12 million Americans have peripheral arterial disease, or PAD, in which clogged or stiffened leg arteries cause pain during walking or rest. Left untreated, PAD can cause non-healing wounds and gangrene, and can led to amputation unless the blocked area is opened or bypassed. It's also associated with a high risk of heart attack and stroke.
The new U-M study looked at the usage rates and effects of statins and ACE inhibitors in 293 patients with advanced PAD who had open-leg bypass operations at the U-M Health System between 1997 and 2002. Average follow-up was 17 months.
The fact that the medicines had such a strong effect may not be surprising, Henke says, when you consider that they've been shown to do the same for patients with clogged heart arteries who have heart bypass surgery or angioplasty.
So, Henke and his colleagues suggest that millions more people whose legs hurt because of early-stage PAD should get a full cardiovascular checkup to look at their overall blood vessel health and determine if they could be helped by medication, or by changes in diet, exercise habits and tobacco use.
After all, he notes, the same factors that cause arteries in the heart to narrow or become blocked -- including high cholesterol, high blood pressure, tobacco use, diabetes and lack of exercise -- affect arteries in the legs and arms too.
"Many of the same strategies that help heart patients do better have also been shown to help PAD patients reduce their pain and increase their walking distance, including exercise, quitting smoking and lowering cholesterol and blood pressure," says Henke. "It stands to reason that the same medications could help, too -- this is a systemic, whole-body disease."
Henke and his colleagues were dismayed to find that even though scientific evidence shows statins and ACE inhibitors can help overall cardiovascular health, about half of the PAD patients studied had gotten all the way to surgery without taking them.
"These were all patients who were having infrainguinal bypass surgery to address severe pain and non-healing wounds, or to save their legs from amputation, but many of them apparently had gone without the kind of whole-body cardiovascular care that might have led to the use of one or more of these drugs," says Henke.
However, the vast majority (93 percent) were taking one or more blood-thinning drugs to reduce pain and prevent blood clots, mostly aspirin but also prescription drugs clopidogrel and warfarin.
The patient population studied was two-thirds male, and about one-third were smokers. Besides their severe, limb-threatening PAD, they had a high rate of other diseases, including hypertension (70 percent), diabetes (52 percent), high blood cholesterol (37 percent), coronary heart disease (51 percent) and heart failure (14 percent). Thirty-nine percent had graft surveillance, or regular monitoring of the status of their bypass graft using ultrasound.
The bypass grafts used in their operations were mainly the patients' own veins, taken from the leg or other parts of the body. These autologous grafts, as they are called, are known to be superior to artificial grafts, which use synthetic tubes. But 88 of the 338 grafts done on the patients in the study were artificial, and 32 were a combination -- most likely because those patients' eligible veins had already been used for other leg or heart bypass operations.
In all, the results show that the 56 percent of patients who had been on statins before their leg bypass were more than three-and-a-half times as likely as non-statin users to have good flow through their bypass grafts in the follow-up period. They were also significantly less likely to require an amputation during the follow-up period.
Meanwhile, the 54 percent of patients who were taking ACE inhibitors before surgery were far less likely to die during the follow-up period than those who had not been taking them.
The bottom line, Henke says, is that vascular surgeons need to familiarize themselves with the best medical evidence about cardiovascular drugs, and follow guidelines for their use.
This is especially true as vascular surgeons and interventional cardiologists both increase their use of minimally invasive procedures for clogged vessels in the legs and other areas of the body.
And, he notes, it's important for people to tell their regular doctors if they feel leg pain when they walk or while they're at rest. The symptoms of PAD often go unreported, and only if patients speak up about the pain they're feeling can they get the early intervention -- diet, exercise, lifestyle changes, medications -- which can prevent them from needing risky leg bypass surgery.
This is especially true for diabetics. A newly released recommendation from the American Diabetes Association urges all diabetics over the age of 50 to get tested for PAD by checking the blood pressure in their ankles.
In addition to Henke, the study's authors are Susan Blackburn, MBA, Mary C. Proctor, M.S., Jeri Stevens, M.S., Debabrata Mukherjee, M.D., Sanjay Rajagopalan, M.D., Gilbert Upchurch, M.D., James Stanley, M.D., and Kim Eagle, M.D., all of the U-M Cardiovascular Center.