Study targets high-risk cardiac patients with a flu vaccine dose that is four times stronger than the standard potency.

Heart disease patients enrolled in a clinical trial – designed to test whether a stronger dose of the influenza vaccine can prevent death or hospitalization due to a heart attack, heart failure, stroke or pneumonia – have begun receiving their first flu shots in Toronto and Boston.

Spearheaded by researchers from the Peter Munk Cardiac Centre, University Health Network (UHN) and Women’s College Hospital, this first, large-scale North American study is a collaboration of numerous healthcare centres in Canada and the United States that are taking part in the Influenza Vaccine to Effectively Stop Cardio Thoracic Events and Decompensated Heart Failure (INVESTED) trial. This trial is supported by the National Heart, Lung and Blood Institute (NHLBI) of the National Institutes of Health (NIH).

“As the Canadian leaders in this extensive study, our multi-disciplinary team of cardiac and vascular scientists, researchers and global clinical trials specialists are poised to potentially alter how this large group of already-susceptible heart patients is managed,” says Dr. Barry Rubin, Medical Director, Peter Munk Cardiac Centre, UHN.

“An investigation of this scope that is focused on testing a potential new approach to prevent deteriorating health or death in heart failure and heart attack patients is significant,” he says.

Supported by a $21 million grant from the NIH, INVESTED will test the efficacy of two different formulations of the influenza vaccine — the standard dose and a stronger dose — in patients with heart failure or patients who have had a heart attack in the previous year. The test will determine which vaccine better protects these patients from having their heart and lung conditions worsen so that they require hospital admission, or become fatal.

“Research has shown that the standard flu vaccine may prevent heart attacks but it does not provide enough of an immune boost or protection for patients with a cardiac condition”, says Dr. Jacob Udell, cardiologist, Peter Munk Cardiac Centre and Women’s College Hospital, Assistant Professor of Medicine, University of Toronto, and one of the Canadian co-Principal Investigators in INVESTED.

“Given that more heart disease patients die as a result of the flu than any other chronic health condition, and that the standard flu vaccine has been found to reduce the risk of heart attack in these patients, perhaps a stronger dose flu vaccine could provide even greater benefit and now is the time to definitively answer this question” he says.

Over the next four flu seasons, some 9,000 patients will be enrolled in INVESTED across 180 clinics and hospitals across North America.

“If successful, the public health impact could be substantial, says.” Dr. Scott Solomon, cardiologist, Boston’s Brigham and Women’s Hospital and Harvard Medical School professor, and one of the American co-Principal Investigators in the trial.

Influenza kills about 3,500 Canadians and 36,000 Americans, each year.