People with certain blood types have a higher risk of having a heart attack when there is significant air pollution, a new study has found.
Researchers in the US found that individuals who have A, B, or AB blood types have an elevated risk of having a heart attack during times of high pollution, compared to those with the O blood type.
The ABO gene - which is present in people who have A, B, and AB blood types - is the only gene validated in large international studies to predict heart attacks among people with coronary disease.
Previous studies have also shown links between tiny particles of air pollution and heart attacks, admission to the hospital with chest pain, heart failure, and irregular heartbeat.
"We wondered, if someone has a specific variation in this ABO gene, are they more or less likely to experience a heart attack in times of higher pollution?" said Dr Benjamin Horne, a clinical epidemiologist and lead researcher at Intermountain Medical Center Heart Institute in Salt Lake City.
“The primary mutation we studied differentiates between O blood types and non-O, which includes positive and negative A, B, and AB blood types. The one that’s been found in genetic studies to be lower risk is O. The other three were higher risk.”
Dozens of genes predict the onset of coronary artery disease in people who are free of the disease. But the vast majority of people will not have a heart attack unless they already have coronary artery disease.
“You have to have other characteristics for coronary disease to progress to a heart attack,” Dr Horne said.
Nothing to panic over
“The association between heart attacks and pollution in patients with non-O blood isn’t something to panic over, but it is something to be aware of.”
Almost half the population in Ireland (47 per cent) has the blood group O positive. AB negative is the least common, accounting for just 1 per cent of the population.
Some 26 per cent of people are type A positive, 9 per cent are B positive, 8 per cent O negative, 5 per cent A negative and 2 per cent B negative. Just 2 per cent of the population has the AB positive blood type.
The results of the study by the Intermountain Medical Center Heart Institute and Brigham Young University were reported at an American Heart Association conference in California on Tuesday.
The researchers had already identified that a level of 25 micrograms of pollution per cubic metre of air resulted in an increased risk occurred for people with non-O blood types.
“Two years ago we published findings that showed once you go above that, each additional 10 micrograms of pollution per cubic meter of air provided substantially higher risks,” Dr Horne said. “At levels higher than 25 micrograms per cubic meter of pollution, the increase in risk is linear, while below that level there’s little if any difference in risk.”