AHA: More testing does not facilitate better heart disease diagnosis
Performing additional diagnostic testing—C-reactive protein and coronary calcium scoring, among others—does not produce better findings, according to an expert consensus document released at the annual American Heart Association (AHA) meeting Nov. 15. Assessing cholesterol levels, blood pressure, age, sex, family history, smoking and incidence of diabetes is still the best risk assessment tool to predict heart disease.

The experts determined that to maximize the benefits of prevention-oriented interventions, global cardiovascular risk score and family history should be tested in asymptomatic people starting at age 20.

“There’s strong evidence that the basic risk assessment we’ve been advocating for years has a very, very strong ability to predict risk,” said Philip Greenland, MD, a professor of medicine and preventive medicine at Northwestern University Feinberg School of Medicine in Chicago, and chair of the guideline writing committee. “When new tests compete for attention we have to ask, ‘Do they add any new information?’”

The researchers assessed whether new tools and tests could change treatment plans or physician outcomes and whether or not they would improve health outcomes. The authors found that often, tests were only useful for patients at intermediate risk of heart disease—those with a 10 to 20 percent risk of developing heart disease within 10 years.

Thus, they say that for low-risk patients, diagnostic testing seldom adds “useful predictive information, while in high-risk patients, the global risk score and family history make it obvious what the physicians should do next, and additional tests don’t change that.”

“Some people say that if you improve risk prediction you can assume you’ll improve patient outcomes, but it’s not so clear. All prediction does is give the physician different information and the patient a different message. But those two things have to be potent enough to change what happens next. If you’re going to come out with a recommendation that a test should be done for everybody, it’s important to be confident of better patient outcomes,” said Greenland.

The experts concluded that the following tests may be considered appropriate in adults for cardiovascular risk assessment:

  • C-reactive protein, in intermediate-risk men age 50 and younger and women age 60 and younger, for cardiac risk assessment, plus a select group of older people, for determining whether statin therapy is warranted;
  • Coronary artery calcium scoring, in people with diabetes age 40 and older, in intermediate-risk people and, possibly, those at low-to-intermediate risk;
  • Resting ECG, especially in people with high blood pressure or diabetes;
  • Ankle-brachial index, in intermediate-risk people, to test for atherosclerosis in the arteries of the legs;
  • Carotid intima-media thickness, in intermediate-risk people, to test for atherosclerosis in the carotid arteries;
  • Microalbuminuria, in intermediate-risk people or those with high blood pressure or diabetes, to test for early signs of kidney damage;
  • Conventional echocardiography, in people with high blood pressure, to check for thickening of the heart muscle;
  • Nuclear stress testing, in people with diabetes or a strong family history of heart disease, when previous tests suggest a high risk for heart disease;
  • Exercise ECG stress test, in intermediate-risk people, for example, before starting a vigorous exercise program;
  • Hemoglobin A1c, in people with or without diabetes, to gauge average blood sugar levels over time;
  • Lipoprotein-associated phospholipase A2, in intermediate-risk people.

“Knowing whether a person is at low, intermediate or high risk helps a physician tailor therapy for that specific person,” Greenland said. “There are a lot of tests out there and a lot of claims that these tests are valuable for risk assessment. This guideline puts it all in perspective.”

However, the researchers concluded that more research is necessary to outline the most optimal timing to begin risk assessments and repeat risk assessments in asymptomatic patients. Additionally, research is limited on the best way to make informed decisions about the frequency of risk assessment in persons deemed at low or intermediate risk.

Lastly, researchers are begining to answer whether genetic testing, socioeconomic factors or MRI are established cardiovascular tests that can properly assess cardiovascular risk.

“Studies that evaluate the specific testing strategy against a specific patient-centered outcome are needed. In addition, comparative effectiveness of various test strategies is needed to determine costs, benefits, and comparative benefits of competing testing approaches,” the authors concluded,

The guideline was developed in collaboration with the American Society of Echocardiography, American Society of Nuclear Cardiology, Society of Atherosclerosis Imaging and Prevention, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, and Society for Cardiovascular Magnetic Resonance and will be published in the Dec. 14/21 issue of the Journal of the American College of Cardiology and in the Dec. 21 issue of Circulation: Journal of the American Heart Association.