The vaccine's heart protective effects may be even greater among those who receive a more potent vaccine, found the study led by Dr Jacob Udell, a cardiologist at Women's College Hospital and clinician-scientist at the University of Toronto.
"Our study provides solid evidence that the flu shot helps prevent heart disease in vulnerable patients-with the best protection in the highest risk patients," Udell said.
The study reviewed six clinical trials on heart health in people who received the flu vaccine. The studies included more than 6,700 patients with a history of heart disease.
The researchers found people who received the flu shot had a 36 per cent lower risk of a major cardiac event (heart attack, stroke, heart failure, or death from cardiac related causes) one year later.
They also had a 55 per cent lower risk of a major cardiac event if they had a recent heart attack and were less likely to die from cardiac-related and other causes.
Those who received the flu shots were also less likely to have a major cardiac event with a more potent vaccine compared with the standard seasonal vaccine, the study found.
However, researchers caution that a large prospective clinical trial is necessary to confirm the effectiveness and safety of the influenza vaccine as a therapy that will reduce the risk of heart attack or stroke in people with heart disease.
The study was published in the Journal of the American Medical Association.