At Martin O’Riordan’s cardiology practice in the Philadelphia area, it happens weekly.
A 45- or 50-year-old patient mentions that her father had a heart attack at the same age. Worried that the same fate will befall her despite being in good health, she takes baby aspirin every day.
O’Riordan’s typical response: Please stop.
Physicians have known for decades that daily, low-dose aspirin makes sense for patients who have had a heart attack or stroke, as it sharply reduces the chance of having a second one.
But for people who have never had one of these cardiovascular “events,” the thinking on aspirin is less clear, despite two recent large-scale studies. The reason for caution is the very reason that aspirin wards off heart attacks and strokes: It interferes with blood clotting, putting the patient at higher risk of serious gastrointestinal bleeding.
Bottom line: Aspirin is more potent than many people realize, said O’Riordan, of Mercy Cardiology.
“People have kind of looked at it as, ‘Aspirin, an apple, a glass of milk, it’s all good for you,’” said O’Riordan, who is on staff at Lankenau Medical Center. “Aspirin is a medication.”
It is a medication drawing renewed scrutiny, 30 years after the Food and Drug Administration approved its use after a heart attack.
Evidence suggests it is also a good idea for some people who have not had a heart attack but who are at risk of having one – those with multiple risk factors such as high cholesterol, high blood pressure or diabetes. But the FDA has not approved it for that use.
And no one is precisely sure at what point aspirin’s benefits outweigh the risk of bleeding, said J. Michael Gaziano, chief of the division of aging at Brigham and Women’s Hospital in Boston.
“We know that it prevents heart attacks in everybody,” said Gaziano, who is helping to oversee one of three ongoing aspirin trials. “What we don’t know is exactly what’s the break point.”
One issue is deciding how much “weight” to assign to a serious bleed. It is generally not as bad as a heart attack, yet some aspirin-related bleeding is severe enough to require a blood transfusion.
Another problem is the low rate of heart attacks in the broader population, which is dropping with healthier lifestyles. Statistically, it is hard to measure a reduction in something that is uncommon to begin with.
Among those who have never had a heart attack or stroke, studies have linked aspirin use with a nearly 12 percent reduction in the chance of suffering one. But that is a reduction in a very small number. Instead of 57 heart attacks and strokes per year in a group of 10,000 people, you get 51, according to a meta-analysis published in the Lancet.
The impact on serious bleeding, meanwhile, varies from study to study. As with the drop in heart attacks, however, the yearly increase in major bleeds per 10,000 people is in the single digits – though higher in older people.
O’Riordan and other physicians use one of several “risk calculators” to determine a patient’s chance of a cardiovascular event in the next 10 years, generally recommending aspirin if that risk is above 6 to 10 percent.
Researchers have found that some of these calculators, popular online, may overestimate the chance of a heart attack. The most recent evidence was published recently in the Annals of Internal Medicine.
Still, the numbers are compelling enough for Cherry Hill, Pa., resident Frank Plunkett, who has not had a heart attack but who has taken daily aspirin for more than a decade.
Plunkett has high blood pressure and a total cholesterol count that at times has exceeded 200, so his physician told him aspirin was a good bet.
“I think it helps prevent clots and keeps my blood vessels from getting clogged,” said Plunkett.
The FDA has taken a more cautious stance. Last spring, the agency rejected Bayer HealthCare’s request to market low-dose aspirin for use by people who have not had a heart attack.
Yet many people take it – even those who are at low risk of heart disease, according to a January study in the Journal of the American College of Cardiology.
In a population of nearly 69,000 patients at 119 cardiology practices, study authors found 11.6 percent were taking aspirin despite having less than a 6 percent risk of cardiovascular disease in 10 years.
That number reflected only those for whom aspirin use was recorded in the physician’s chart. So the rate of people taking aspirin inappropriately may actually have been higher, said lead author Ravi S. Hira, an interventional cardiology fellow at Baylor College of Medicine in Houston.
Though the “worried well” sometimes take aspirin when they should not, studies have found some heart attack victims fail to take it even though they should, said Garret FitzGerald, a professor at the University of Pennsylvania’s Perelman School of Medicine.
The first clues that aspirin could prevent heart attacks came in the late 1940s, when California physician Lawrence Craven noticed patients who had their tonsils removed were prone to bleeding if they took aspirin for the pain. He hypothesized the medicine might interfere with the formation of clots that can lead to heart attacks, and science eventually proved him right.
In the 1980s, FitzGerald and his Penn colleagues conducted some of the key research leading to a consensus that even a low dose of the drug could prevent a second heart attack.
More recent research suggests aspirin may have another benefit. Studies have associated it with a reduced rate of colon cancer, though FitzGerald called that “an interesting suggestion rather than compelling evidence.”