A study published on Tuesday suggesting cardiac patients get vaccinated against flu showed that heart problems may account for a huge share of deaths from influenza, AFP reported.
The study looked at mortality figures for acute myocardial infarction — a sudden heart attack — and cardiovascular disease during outbreaks of flu between 1932 and 2008.
The research, which was published in the journal Lancet Infectious Diseases, did not however include the current pandemic H1N1 virus.
Cardiovascular problems were attributed to between 35 and 50 percent of the increase in deaths recorded during influenza outbreaks.
Infectious disease epidemiologists Charlotte Warren-Gash and Andrew Hayward at University College London found that the flu virus causes inflammation and acts on the molecular pathways that control blood coagulation.
They went on to add that those effects could destabilize fatty deposits that line the arterial wall and cause clots that block coronary arteries.
The paper noted that only a few investigations have been carried out into whether flu vaccination helps protect cardiac patients, but the little evidence available suggests it does.
The authors wrote: “We believe influenza vaccination should be encouraged wherever indicated, especially in those people with existing cardiovascular disease.”
Many countries currently recommend vaccines for “seasonal” flu for individuals with chronic medical conditions that generally include cardiovascular disease but not other cardiac problems such as hypertension.
But figures quoted in the study show that relatively few people at risk take up the vaccine. Only 47.2 percent of people with chronic conditions received the seasonal flu vaccine in Britain and only about one-third of heart patients in the U.S. regularly get vaccinated.
It is still unclear whether the study results apply to otherwise healthy people with no history of heart disease. But they say flu viruses could potentially trigger heart attacks in people who have risk factors like high blood pressure or are overweight but show no apparent heart disease.
Dr. Harlan Krumholz, a spokesman for the American Heart Association and professor of medicine at Yale University, said flu has too often been off the radar screen.
“But flu is as important to think about as cholesterol or blood pressure,” he added.
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