Evaluating heart risk in asymptomatic patients
In coronary atherosclerosis, plaque narrows the diameter of the arteries.
Tests designed to assess risk of cardiovascular disease have multiplied in recent years. But most asymptomatic patients need few, if any, tests beyond standard lipid profiles and BP measurement, according to a guideline from the American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA).1
"This is a strong endorsement of standard risk assessment based on traditional risk factors," said Philip Greenland, MD, professor of preventive medicine and medicine at Northwestern University's Feinberg School of Medicine and chair of the committee that wrote the guideline. "In our estimation, there isn't a single [additional] test that should be used on all healthy people."
The most important measure of cardiovascular risk in patients without symptoms, the authors emphasized, is a global coronary and cardiovascular estimate such as the Framingham Risk Score, which uses age, weight, BP, lipid parameters and smoking status to assign patients to low-, intermediate- and high-risk categories (generally <10%, 10-20%, >20%, respectively), based on the likelihood of a cardiovascular event occurring within the next 10 years.
The ACCF/AHA guideline endorses further testing "only in patients where the primary-care practitioner might feel uncertain after this risk assessment — typically those at 'intermediate' risk," Greenland explained. Those at low risk generally need nothing beyond lifestyle modification, and it is unlikely that further testing will change treatment of those already judged to be at high risk.
Although family history should be ascertained, it only modestly adds to the predictive power of global assessments, generally for patients at intermediate risk, the guideline authors wrote.
Some tests may be useful when patients are unconvinced of the need for treatment based on such risk indicators as elevated cholesterol, Greenland affirmed. "If something like an imaging test is abnormal, it's another piece of information that we can use to motivate the patient."
The guideline does not recommend any test unequivocally. At best, an assessment is described as "reasonable" or "useful" for specific groups; it "may be considered" for certain patients when evidence of utility is weaker.
Lab tests beyond cholesterol
Tests are available to measure lipid parameters beyond the standard profile, including lipoprotein, apolipoprotein, particle size and density. None of these tests are recommended for asymptomatic patients.
C-reactive protein (CRP), an index of inflammatory activity believed to be a key process in atherosclerosis, has been the subject of considerable interest in recent years. The ACCF/AHA guideline recommends the test, but in a qualified way. Only one randomized controlled trial has provided data substantiating the utility of CRP in guiding treatment, Greenland noted.
CRP testing "can be useful" in statin therapy selection among men aged 50 years or older and women aged 60 years or older with LDL levels <130 mg/dL, who are not on lipid-lowering drugs or hormones and who are without diabetes, chronic kidney disease or severe inflammatory conditions, the authors suggested.
CRP received a weaker endorsement for younger individuals judged to be at intermediate risk, with the committees stating that it "may be reasonable," for these patients. CRP testing is not recommended for high-risk individuals and younger people at low risk.
The American Diabetes Association has endorsed hemoglobin (Hb)A1c as a screen for diabetes. Based on several studies associating HbA1c elevations with increased risk of CVD, the guideline authors gave the test a weak recommendation for asymptomatic individuals without diabetes.
A similar endorsement was given to the use of lipoprotein-associated phospholipase A2 for intermediate-risk adults.