Patients suffering from two serious autoimmune disorders which cause muscular inflammation are at increased risk of developing cardiovascular disease, says a group of Montreal researchers. Dr. Christian A. Pineau and his team at the Research Institute of the McGill University Health Centre (RI-MUHC) have linked muscular inflammation to increased cardiovascular risk for the first time. Their results were published recently in The Journal of Rheumatology.

Polymyositis (PM) and dermatomyositis (DM) are most common in women and seniors, although they can affect people of any age. Both diseases are caused by a hyperactive immune system which attacks healthy tissue, almost as if the body had become allergic to itself. This causes serious inflammation of muscle tissue in the body, leading to weakness, reduced mobility and, in the case of DM, rashes. Muscles in the heart and the lungs may also be affected.

"Inflammation has recently been recognized as a risk factor - along with hypertension and cholesterol problems - for arterial diseases that can lead to events such as heart attacks," says Dr. Pineau. Nearly one in 5,000 people suffer from PM and DM, approximately 7,000 in Canada and 75,000 across North America.

"Our results indicate that the risk of heart attack is twice as high in these people as in the general population," says Dr. Sasha Bernatsky, a study co-author. "Each year, one out of every 200 people with muscle inflammation, or myositis, succumbs to a stroke and one out of 75 to a heart attack."

The researchers also noted that the immunosuppressive therapies currently used to treat PM and DM may have a preventive effect against heart attacks. "This is an extremely interesting finding for patients who are suffering from PM and DM but who may be hesitant to undergo this type of treatment," adds Dr. Pineau, noting that some patients are concerned about the possible side-effects of immunosuppressive therapies, such as reduced immunity to infection.

"Sometimes patients do not want to undergo immunosuppressive treatment, which can last for years," adds Dr. Bernatsky. "Knowing that it has additional preventive effects may help some people decide to opt for the treatment."

Cardiovascular diseases are the world's leading cause of death, and the researchers hope that their results will provide a clearer picture of the possible benefits and possibilities of immunosuppressive treatment. As a result of their encouraging findings, Dr. Pineau and his team are now turning their attention to possible benefits of immunosuppressive therapy on other health risks associated with inflammatory diseases.

Partners
This article was co-authored by Dr. Annaliese Tisseverasinghe of the MUHC, and Drs. Sasha Bernatsky and Christian A. Pineau of RI-MUHC and McGill University.

Funding
This study was funded by a grant from the Canadian Institutes of Health Research (CIHR).
Dr. Sasha Bernatsky is a researcher in the RI-MUHC Musculoskeletal Disorders Axis, and a doctor in rheumatology and epidemiology at the MUHC clinic. She is also an assistant professor in the McGill University Faculty of Medicine.
Dr. Annaliese Tisseverasinghe is a former internal medicine resident at the MUHC. She is currently pursuing her studies in rheumatology.
Dr Christian A. Pineau is a researcher in the RI-MUHC Musculoskeletal Disorders Axis, as well as co-director of the lupus and Vasculitis clinic at the MUHC. He is also the Rheumatology Program Director and associate professor in the McGill University Faculty of Medicine.

Source:
Julie Robert
McGill University Health Centre