News

Research Update - Respiratory Infections Can Trigger a Heart Attack

Oct 19, 2017

New research from the co-located Ramsay North Shore Private/Royal North Shore Hospital Cardiac Catheterisation Laboratory in Sydney finds the risk of a heart attack is increased 17-fold in the week following a respiratory infection such as influenza or pneumonia.

Published in the May 2017 edition of Internal Medicine Journal, this is the first study to report an association between respiratory infections such as pneumonia, influenza and bronchitis and increased risk of heart attack in patients confirmed by coronary angiography (a special X-Ray to detect heart artery blockages).

“Our findings confirm what has been suggested in prior studies that a respiratory infection can act as a trigger for a heart attack," said senior author Professor Geoffrey Tofler, cardiologist at North Shore Private and Royal North Shore Hospitals, and Honorary Medical Director of Heart Research Australia.

“The data showed that the increased risk of a heart attack isn't necessarily just at the beginning of respiratory symptoms, it peaks in the first 7 days and gradually reduces but remains elevated for one month. This association is a likely contributor to the known winter peak in heart attacks.”

The study was an investigation of 578 consecutive patients with heart attack due to a coronary artery blockage, who provided information on recent and usual occurrence of symptoms of respiratory infection.  Patients were interviewed about their activities before the onset of their heart attack, including if they experienced a recent “flu-like illness with fever and sore throat”. They were considered affected if they reported sore throat, cough, fever, sinus pain, flu-like symptoms, or if they reported a diagnosis of pneumonia or bronchitis. 

“Our message to people is while the absolute risk that any one episode will trigger a heart attack is low, they need to be aware that a respiratory infection could lead to a coronary event. So consider preventative strategies where possible, and don’t ignore symptoms that could indicate a heart attack.

Flu and pneumonia vaccines, where appropriate, are an important way to lower risk. Besides those eligible for free vaccine, including people  aged over 65 years, or with known cardiac or respiratory disease, the flu vaccine is recommended for hospital staff and others who come in contact with people at higher risk of influenza complications.

Professor Tofler added: “Possible reasons for why respiratory infection may trigger a heart attack include an increased tendency towards blood clotting, inflammation and toxins damaging blood vessels, and changes in blood flow.”

“The next step is to identify treatment strategies to decrease this risk of heart attack, particularly in individuals who may have increased susceptibility.”

Further information on this research and other heart related issues is available on the Heart Research Australia website www.heartresearch.com.au.