SAN DIEGO — Consider expanding subclinical cardiovascular disease testing to include asymptomatic high-risk patient populations, Leslee J. Shaw, Ph.D., advised attendees at the annual meeting of the American Society of Nuclear Cardiology.
Primary care physicians considering which patients to refer for evaluation should ask themselves in which of their appropriate patients they can identify risk of cardiovascular disease, suggested Dr. Shaw, professor of medicine at Emory University, Atlanta. “The goal is to expand cardiovascular testing to improve the detection gap. But we have to do it appropriately, without excessive cost.”
One ideal population to target with subclinical testing is the high-risk elderly. A recent study found that 1 in 5 people aged 65 years and older has an ankle brachial index of less than 0.9, yet only 1 in 10 peripheral artery disease patients will have classical symptoms of intermittent claudication (Atherosclerosis 2004;172:95–105). “If one relies solely on classical symptoms of intermittent claudication, you will underappreciate the prevalence of peripheral artery disease,” said Dr. Shaw, who is also an outcomes research scientist for the Emory Program in Cardiovascular Outcomes Research and Epidemiology. “So in this population of patients, perhaps ankle brachial index or some other modality may be good at identifying asymptomatic patients who are at risk of worsening outcome.”
Other populations to target include:
▸ High-risk functionally impaired patients. Patients who can't achieve 5 METs on the treadmill test “are functionally impaired and have a high risk for cardiovascular events,” she said. “We need to do a better job of not only identifying the degrees of comorbidity, but treating their comorbidities, perhaps getting them to improve their exercise abilities to lessen that risk. There [are] a lot of data showing that these patients can improve their exercise tolerance and can have an improved outcome following cardiac rehabilitation.”
▸ High-risk smokers. Smoking is a leading cause of acute coronary thrombosis. Dr. Shaw and her associates showed in a recent study that patients who smoke and have coronary calcification have a worsening mortality, compared with nonsmokers (Eur. Heart J. 2006;27:968–75). “Young smokers with a lot of coronary calcification have an anticipated loss in life expectancy of 4–5 years,” she said. “This is a good message for young smokers, especially patients in their 40s who have children. Five years is a lot to lose of your life.”
▸ Asymptomatic diabetics. Diabetes patients who are candidates for subclinical cardiovascular disease testing include those with poorly controlled diabetes, those who have not achieved their LDL cholesterol goal, those with multiple cardiac risk factors, and those who have had diabetes for more than 5 years.
In this population of patients “you might want to think about assessing the baseline cardiovascular risk, consider ischemia testing in those with a high-risk scan, and look for disease progression downstream,” Dr. Shaw said.
She called coronary calcification “an amazing prognostic test.” The overall rate of perfusion abnormalities is high in diabetic patients with a calcium score of 100 or higher.
▸ Patients with metabolic syndrome. The National Cholesterol Education Panel Adult Treatment Panel III defines the criteria for metabolic syndrome as three or more of the following: abdominal obesity (a waistline greater than 102 cm in men and greater than 88 cm in women); triglyceride levels of 150 mg/dL or greater; HDL cholesterol levels of less than 40 mg/dL in men and less than 50 mg/dL in women; a systolic blood pressure of 130 mm Hg or greater or a diastolic blood pressure of 85 mm Hg or greater; and a fasting glucose level of 110 mg/dL or greater.
A recent study showed that the prevalence of inducible ischemia is increased among patients with metabolic syndrome who do not have diabetes, as well as in those who have diabetes, when their calcium scores exceed 100 (Diabetes Care 2005;28:1445–50).
In these patients, “think about retesting with perfusion imaging,” Dr. Shaw advised.
▸ High-risk women. This includes those with early menopause, those with autoimmune disease, and those with polycystic ovary syndrome. All conditions confer an increased risk of coronary artery disease.
Dr. Shaw emphasized that by targeting high-risk patient populations, you are not screening, you are testing. “So in discussions with payers, tell them that you are trying to identify appropriate testing candidates and minimize inappropriate testing in your testing practice,” she explained. “The goal is to identify patients who require more intensive management and thereby decrease the detection gap of high-risk patients with a resulting … improvement in cardiovascular mortality.”