ASE: Vascular Ultrasound Finds Unsuspected Arterial Plaque

SEATTLE, June 19 -- Preclinical atherosclerosis, often missed by conventional risk assessment, can be broadly identified by vascular ultrasound, investigators said here.

More than 40% of an unselected group of men and women had evidence of preclinical atherosclerosis detected by ultrasound, said John Postley, M.D., of Columbia in New York, and colleagues, at the American Society of Echocardiography meeting.

The total included 35% of women and 25% of men categorized as low risk by the Framingham Risk Score, the investigators added.

The results suggest that screening with vascular ultrasound could help reduce the burden of coronary disease, said Dr. Postley.

"Every year 600,000 people have a first myocardial infarction, which carries a 40% death rate for men and women," he said. "Traditional risk analysis, as embodied in the Framingham Risk Score, has very low specificity, particularly in women. We need to identify ways of finding these people before their initial event, which may be death."

Ultrasound screening should include the femoral and carotid arteries, he added. In 21% of cases, plaque was detected only in the femoral arteries.

The findings came from a study of 398 patients (47% women) recruited from 14 internists' practices. Patients were 33 to 79 years old, and a Framingham score was available for 353. Investigators excluded patients who had a history of angina, MI, stroke, claudication, or treatment for dyslipidemia.

By Framingham Risk Score assessment, 32% of men had a low 10-year probability of cardiovascular events, 41% had an intermediate risk, and 25% had a high risk. Among women, 71% were low risk by Framingham Risk Score, 25% were intermediate risk, and 4% were high risk.

Overall, 43% of the patients had atherosclerotic plaque detected by ultrasound, including 45% of men and 40% of women. Distribution of plaque by Framingham Risk Score was:

• Low risk-25% of men, 35% of women
• Intermediate risk-49% of men, 60% of women
• High risk-72% of men, 43% of women

The findings are particularly pertinent to women, Dr. Postley noted. Chi-square analysis showed no difference in the rate of plaque among low-, intermediate-, and high-risk women.

In 43% of cases, plaque was found only in the carotids, and plaque was limited to the femoral arteries in 21% of cases.

"This shows that screening of the femoral arteries is important," said Dr. Postley. "If screening had been limited to the carotid arteries, the plaque would have been missed more than 20% of the time."

The findings have a precedent in an Italian study reported several years ago (Belcaro et al. Atherosclerosis. 2001;156:379-387). That study involved 10,000 low-risk patients who had ultrasound screening of the carotid and femoral arteries.

During 10 years of follow up, 98.5% of clinical events occurred in patients who had ultrasound abnormalities. The incidence of events correlated directly with the severity of imaging abnormalities. Consistent with Dr. Postley's data, 30% of ultrasound-detected plaque was found only in the femoral arteries.