COX-2 inhibitor increases the risk of heart attack in elderly adults with no history of heart attack

02/01/05

New research published in the on-line version of the Annals of Internal Medicine today, documents an increased risk of heart attack with one of the COX-2 inhibitors used in elderly adults with no previous history of heart attack--a group previously considered low-risk.

The study, sponsored by the Canadian Institutes of Health Research (CIHR) and conducted by researchers at the McGill University Health Centre (MUHC) in Montreal, examined the relationship between the use of all nonsteroidal anti-inflammatory drugs (NSAIDs) and the risk of heart attack in 113,927 Quebec senior citizens. Only one of these agents, a COX-2 inhibitor called Vioxx--a new class of NSAIDs--carried a greater risk of heart attack.

"Many believe that COX-2 inhibitors increase the chance of a heart attack in high risk groups, for example people who have already suffered a heart attack," explains primary author Linda Lévesque, a pharmacist and McGill University PhD candidate in the Department of Epidemiology and Biostatistics. Lévesque worked with co-author Dr. James Brophy, a cardiologist and Director of the Technology Assessment Unit (TAU) at the MUHC and Associate Professor of Medicine at McGill University. "This study demonstrates the overall risk of heart attack is increased 24% for users of Vioxx who have not previously suffered a heart attack," Lévesque says.

The study also reveals that aspirin use can help offset the damaging effects of Vioxx. "Aspirin mitigates the risk to individuals," confirms Lévesque. "But only in those on a low dosage of Vioxx."

The study also demonstrates that the increased risk of heart attack is only present while taking the drug. "Past users of Vioxx were not at increased risk," explains Lévesque. "While the risk more than doubles for those who are taking high doses of the drug even when using aspirin."

COX-2 inhibitors are commonly used to relieve the pain and inflammation caused by arthritis in the elderly. These drugs are believed to increase the 'stickiness' of blood platelets--the tiny bodies that assist in blood clot formation. "It is possible that stickier platelets increase the chance of a blockage forming in a blood vessel of the heart," explains Lévesque. "This study contributes to the growing body of evidence concerning the cardiac safety of COX-2 inhibitors."

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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