If you’re dealing with heart disease, you’re likely following a treatment plan from your doctor—as you should.

But you should also be aware that according to a new study, led by the Duke University Clinical Research Institute, more than 90% of heart disease treatment guidelines stem from less-solid science—evidence that came from just a single trial or observational analyses, or from expert opinion.

The study, published today in JAMA, found that only 8.5% of the treatment guidelines doctors follow for people with heart disease are based on gold standard research—meaning that the evidence is based on multiple large, randomized, clinical trials.

Only 8.5% of the treatment guidelines doctors follow for people with heart disease are based on gold standard research.

The study’s researchers reviewed the science behind more than 6,300 recommendations from the American College of Cardiology and the American Heart Association and the European Society of Cardiology. They were following up on a 2009 study which found that 11% of treatment guidelines met the gold standard.

What’s been proven to work

That doesn’t mean, of course, that all treatment plans lack solid evidence. Experts say the following regimens are well-supported:

Prescription medication. All drugs need to have serious research backing them before the FDA approves them for the market. “Look at the way we’ve reduced heart attacks since statins have been out. There’s good data that statins are partially responsible for that,” says Nieca Goldberg, medical director of the Joan H. Tish Center for Women’s Health at NYU Langone Medical Center.

Exercising regularly and quitting smoking. There’s a lot of evidence that people who exercise and are active live longer, healthier lives, Goldberg says. Smoking, of course, is bad for you for lots of reasons, not just your heart health.

Daily aspirin. “Evidence is very strong for aspirin in people with existing heart or vascular disease,” Goldberg says. And studies are fine-tuning the recommendations for aspirin use for others.  

There’s also reasonable evidence for medical devices, like internal defibrillators and pacemakers, says lead author Alexander Fanaroff, an interventional cardiologist an the Duke Clinical Research Institute.

Where the evidence is lacking

By contrast, one area where doctors commonly offer advice—diet—actually lacks for solid evidence for treatment plans, says Fanaroff. Controlling your sodium is one area where we don’t have good evidence, he points out.

“There’s a real lack of evidence is in dietary [recommendations].”
Cardiologist Alexander Fanaroff

Fanaroff also says that there also isn’t much evidence for treatments for valvular heart disease, a condition in which one of the four heart valves has a defect or is otherwise damaged. Same goes for treating congenital heart disease in adults: “Less than 2% [of treatments] are supported by evidence from randomized, controlled trials.”

That’s because for conditions like these, there simply aren’t as many people to study—it’s easier to research high blood pressure and high cholesterol levels, since so many people have these conditions.

In fact, the areas that were studied most often in randomized controlled trials had more gold standard research supporting them. Still, they came in under 33%. 

Asking the right questions

Given the lack of well-supported evidence surrounding certain treatments, it’s important to press your doctors for details.

When doctors look at treatment guidelines, they can see information about how strong the recommendation is and what evidence is behind it, says Peter Reyes, a cardiologist with The Heart Center at Mercy in Baltimore. So talk to your doctor about your specific condition or treatment.

Ask, “In your best calculation, what are the risks and benefits of the therapy you are recommending?” says Goldberg.