The average Australian adult catches the common cold at least two times a year, generally in winter. Although they are “usually quite harmless”, new research shows they could trigger something usually quite harmful: a heart attack.
The researchers from the University of Sydney asked 891 patients, admitted to Royal North Shore Hospital for suspected heart attack, about their recent health including “whether they had experienced a flu-like illness with fever and sore throat” and whether they had experienced a heart attack previously.
Professor Geoffrey Tofler and his team found that the risk of a heart attack was 17 times higher in the seven days following a cold or respiratory infection including influenza, pneumonia and bronchitis as well as upper respiratory infections.
“Possible reasons for why respiratory infection may trigger a heart attack include an increased tendency towards blood clotting, inflammation and toxins damaging the coronary arteries, and changes in blood flow,” Tofler explains of the research published in Internal Medicine Journal.
The danger, he adds, is increased not just among those more at risk of a heart attack.
“The average age of our study population with a heart attack and prior respiratory infection was 56.4 years,” Tofler says. “While many of the patients had at least one risk factor for heart disease such as high blood pressure (41 per cent) or high cholesterol (48 per cent), only about one in 10 (12 per cent) had a history of a previous heart attack, or previous stent (10 per cent).
“So while the overall risk would be higher in those who already have an elevated risk of heart attack, it also would include people who had no previous warning of heart disease. In half of the patients, there was a blockage in only one coronary artery.”
It is estimated 350,000 Australians have had a heart attack at some time in their lives and heart attacks claim the lives of about 23 Australians each day.
Tofler says the understanding about what triggers heart attacks is changing with time.
“While chronic risk factors, such as high blood pressure, high cholesterol, smoking, diabetes and family history remain of key importance, there is increasing recognition that some more acute factors or triggers, such as a respiratory infection, can destabilise the situation and lead to a heart attack. The well recognised winter peak in heart attacks is likely due in part to more respiratory infections.”
With a heart attack, every minute counts, so knowing the signs and being aware of the risks can make all the difference.
“Our message to people is that while the absolute risk that any one episode of respiratory infection will trigger a heart attack is low, they need to be aware that a respiratory infection could lead to a coronary event,” Tofler says. “They should consider preventative strategies such as flu and pneumonia vaccines, and don’t ignore symptoms that could indicate a heart attack.”