A Danish study found that vaccinated patients with chronic heart failure are less likely to die from a heart attack. The protective effect was most severe if people were vaccinated at the beginning of the flu season.
Why is flu dangerous for heart failure patients?
The influenza virus kills mainly elderly patients with chronic heart failure. A weakened heart muscle is not able to pump the necessary amount of blood, which is needed to fight the virus.
Therefore, European and American societies encourage patients to participate in annual flu vaccines.
Daniel Modin evaluated data from 134,048 patients diagnosed with chronic heart failure over a 12-year period. Data analysis showed that from 16 to 52% of patients took part in annual flu shots. Since then, 77,956 (58%) patients have died, of which 47,966 (36%) from heart attack.
Patients who received at least 1 flu vaccine had an 18% lower risk of death. The protective effect increased with an increase in the number of vaccinations: 2 vaccines reduced the risk of death by 20%. If more than 3 vaccines were used, the risk was reduced by 28%.
A protective effect was found in all flu seasons, with the exception of 2007/2008 and 2015/2016. According to scientists, most diseases were then caused by influenza B, from which the vaccine is useless.
Can a flu cause a heart attack?
A British study showed that the risk of heart attack in healthy people increases 6 times in the first week. Type B influenza infections are the most dangerous form of the disease. An increased risk may also be demonstrated in other acute respiratory infections.
The link between influenza and heart attack was identified in the 1930s.
At that time, it was not possible to detect the virus by laboratory tests. Only with the help of symptoms can the “true” flu be distinguished from acute respiratory infections caused by other pathogens.
Currently, infection with influenza viruses is easily detected by laboratory methods. In practice and in the clinic, this is possible with the help of rapid tests. In unclear cases, biomaterials can be sent to a special laboratory.
344 patients who had not been vaccinated against the flu for a year were more likely to suffer from a heart attack. During the first 7 days after positive laboratory detection of influenza, scientists reported a 6-fold increased risk of heart attack. After the 7th day, the risk of dying from a cardiovascular accident was reduced.
Who is most susceptible to myocardial infarction during the flu?
People with very severe flu are more likely to develop acute myocardial infarction by 8–9 times. Elderly people who are over 65 are especially at risk. The risk of a heart attack is lower in people who have not previously experienced vascular problems.
Patients with chronic heart failure are 4 times more likely to suffer from a heart attack than healthy people.
In addition to flu, other serious respiratory infections can cause a heart attack. Scientists have also found that respiratory syncytial virus and adenoviruses increase the likelihood of vascular obstruction.
All studies unanimously indicate that severe upper or lower respiratory tract infection increases the risk of heart attack.
A heart attack is probably not a direct result of the flu. It is more likely that physical stress or other systemic consequences of the disease cause acute coronary syndrome.
Will a flu vaccine protect even healthy people?
A number of observational studies have suggested that the preventive effect of vaccination against a heart attack helps even healthy people. This is written by a team of cardiologists Jacob Udell from the University of Toronto.
The results were significant: the benefits of vaccination were observed even in healthy people. Scientists also consider this effect to be biologically plausible and confirmed in animal models. 1 vaccine, according to experts, is enough to reduce mortality from cardiovascular disease in the population.
