Despite the fact that clogged arteries in the legs usually mean clogged arteries near the heart, doctors often fail to give heart-protecting drugs to people with severe leg blood vessel blockages, a new University of Michigan-led study finds.
This lack of preventive care in such patients, who are at high risk for a heart attack or stroke, means that more effort is needed to improve the way doctors and patients deal with an often body-wide problem of clogged blood vessels, the researchers say.
In a presentation at the American Heart Association's annual Scientific Sessions, U-M Cardiovascular Center researchers will show data on 553 patients who came to five Michigan hospitals for procedures to re-open clogged blood vessels in their legs and abdomens. Such blockages are called peripheral artery disease or PAD.
The study shows that among such patients, those who also had a history of heart problems were more likely to receive drugs to lower their cholesterol and blood pressure, compared with those who hadn't had heart problems.
"Patients who have severe PAD but haven't experienced heart-related problems are under-treated when it comes to medical therapy, especially statin drugs to lower cholesterol," says senior author P. Michael Grossman, M.D., an assistant professor of cardiovascular medicine who leads the project that produced the new data. "This is despite the fact that national guidelines recommend physicians treat PAD with the same aggressive medical treatment as they treat coronary artery disease."
The patients in the study were all having procedures called peripheral vascular interventions or PVIs, which are nearly identical to angioplasty and stenting procedures performed in blocked or narrowed heart arteries. PVIs are performed on hundreds of thousands of Americans each year, to open blocked arteries in the legs and abdomen that cause disabling leg pain or kidney problems.
Millions more Americans have less-severe blockages, which still put them at higher risk for heart attack and stroke even if they haven't had a history of heart problems. As many as 20 percent of adults may have PAD, but most don't know it -- instead thinking that "old age" is making their legs hurt or feel weak when they walk or rest.
Once diagnosed, the first treatment for PAD patients is to exercise, lose weight and stop smoking -- the same actions that are known to help their hearts. But medicines such as blood thinners, cholesterol drugs, ACE inhibitors and beta blockers, and procedures such as PVI, are used when lifestyle changes don't do enough.
Other treatments are currently being developed, including experimental approaches that use gene therapy or other biological agents to try to encourage the growth of new blood vessels that could take over for blocked vessels.
At the AHA meeting, Grossman will also present results from a multicenter clinical trial he co-led with sponsorship from a company called Valentis. The trial, which compared a pair of Valentis products against one of the products alone, did not show a difference between the two groups of patients with severe leg pain from PAD in terms of the amount of time they could tolerate walking on a treadmill 180 days after treatment.
But the study did show that both groups improved about 34 to 37 percent, including those who had only received a molecule called a poloxamer that may help repair tissue and reduce inflammation. The other group received the poloxamer together with an injected gene for a protein that stimulates blood vessel growth. Now, Grossman leads a trial at U-M comparing poloxamer against placebo.
Other research on agents that might encourage vessel growth is under way or will be soon at the U-M Cardiovascular Center. In the meantime, the PVI project continues to track current treatment.
Grossman notes that the multi-hospital PVI registry that produced the new data is giving him and other researchers a new way to look at how patients with severe PAD are treated -- before, during and after their artery-opening procedures. It also surveys patients on their quality of life.