Flu linked to heart disease deaths

Flu linked to heart disease deaths
Flu linked to heart disease deaths

18 April 2007

MedWire News: Influenza epidemics are associated with a rise in heart disease deaths, say researchers who advocate flu vaccination in patients at high risk for cardiovascular disease.

The international team found that winter peaks in acute respiratory deaths during influenza epidemics were associated with an increase in autopsy confirmed deaths due to myocardial infarction (MI) and chronic ischemic heart disease (IHD). They observed the effect in multiple years, so conclude that a rise in MI and IHD deaths may be anticipated during flu epidemics.

"This calls for more intensive efforts to increase the vaccination rate in people at risk of coronary heart disease, commented lead author Mohammad Madjid (University of Texas, Houston, USA). "This may be especially important in an influenza pandemic when we would expect to see high mortality amongst the elderly and those suffering from heart problems or who have multiple coronary risk factors."

Madjid and colleagues investigated deaths between 1993 and 2000 in St Petersburg, the Russian Federation, for which the documented cause of death on autopsy reports was coronary heart disease.

"Relying on autopsy reports rather than death certificates enabled us to be much more accurate about the cause of death, because doctors often neglect to list flu on a death certificate if their patients have died from a heart attack and, conversely, heart attack symptoms can be missed in patients suffering from flu and pneumonia," Madjid explained.

The results showed that 11,892 people died from acute MI and 23,000 died from IHD. The risk of dying from acute MI increased by one third, and the chance of dying from IHD by one tenth, during epidemic weeks relative to non-epidemic weeks. The effect was seen in both genders and across all age groups.

The researchers believe that acute inflammation in flu can destabilize atherosclerotic plaques causing consequent thrombotic events.

"My public health message is that flu is an important killer in cardiac patients," said Madjid. "If people can recognize that the flu vaccine has specific cardioprotective effects, then high-risk people will be more likely to make sure that they receive the influenza vaccine every year."

He estimates that up to 90,000 coronary deaths a year could be prevented in the USA if every high-risk patient received an annual flu vaccination.

He urged the European Society of Cardiology to follow the lead set in the USA by the American Heart Association and American College of Cardiology and recommend that all at-risk people should be given flu vaccines.

"The vaccine may be even more beneficial for those from deprived socio-economic groups or under-developed countries who are not taking all the recommended cardioprotective medications due to their high cost or lack of access to proper medical care," Madjid added. "The flu vaccine is inexpensive, easy to administer, and could save thousands of lives every year."

He stressed that cardiovascular deaths have surpassed any other causes of mortality, including pneumonia, in most influenza epidemics (except for the 1918 Spanish flu pandemic). Thus, during influenza pandemics, heart disease patients should be considered among priority groups to receive the vaccine or antiviral drugs.

Madjid noted that stockpiling of antivirals such as Tamiflu and progress in developing specific avian flu vaccines should provide sufficient means to combat the next pandemic, provided "nature doesn't take us by surprise this year."

Eur Heart J; 2007; Advance online publication