Washington, DC - Carotid bruits detected by auscultation might serve as markers for heart disease, rather than detect carotid lesions and the subsequent risk of stroke, and could help select patients who would benefit from an aggressive treatment strategy for cardiovascular risk, according to the results of new study [1]. Investigators report that those with carotid bruits have twice the risk of MI and cardiovascular death than those without carotid bruits.

"Our study has shown that the presence of a carotid bruit significantly increased the likelihood of a cardiovascular death or myocardial infarction," write lead investigator Dr Christopher Pickett (Walter Reed Army Medical Center, Washington, DC) and colleagues in the May 10, 2008 issue of the Lancet. "Our findings accord with the notion that these atherosclerotic changes might be indicative of systemwide vascular pathological change to include the coronary bed."

According to the authors, since auscultation of the carotid is a quick and inexpensive test, it could be used to aid clinicians in the assessment of coronary heart disease risk in certain patients. The group points out that the prognostic implications of a carotid bruit have focused primarily on the risk of cerebrovascular events, but carotid bruits are a weak predictor of cerebrovascular events in asymptomatic individuals. For those with symptoms, including nondisabling stroke or transient ischemia in the ipsilateral carotid, prognosis depends more of the severity of stenosis than the presence of a carotid bruit, they write.

Because of these uncertainties, the United States Preventive Services Task Force and the Canadian Task Force recommend against routine auscultation of carotid bruits. However, as Pickett and colleagues note, the turbulent flow in the lumen might serve as a better marker for generalized atherosclerosis and, to test this hypothesis, performed a meta-analysis to assess whether carotid bruits could be used as a prognostic tool in determining in cardiovascular risk.

Overall, 22 studies, with 17 295 patients followed for a median of four years, were included in the meta-analysis. The rate of MI in patients with carotid bruits was 3.69 per 100 patient-years, compared with 1.86 per 100 patient-years in those without carotid bruits. Four studies directly compared the risk of MI in patients with and without carotid bruits and showed that the risk was doubled in patients with detectable carotid turbulence.

In 16 studies, the rate of cardiovascular death in patients with carotid bruits was 2.85 per 100 patient-years, greater than the 1.11 per 100 patient-years observed in four studies assessing risk in patients without bruits. In studies directly comparing the risk of cardiovascular death among those with and without carotid bruits, the risk was more than doubled for those with bruits.

The group notes that a 65-year-old male smoker with uncontrolled hypertension or LDL-cholesterol levels >190 mg/dL would have a similar 10-year risk of coronary events to that conveyed by the presence of a carotid bruit. In addition, the analysis shows that the presence of a carotid bruit meets the definition of a coronary risk equivalent, with a 3.7% risk per year (or 37% risk over 10 years) of cardiac events when the abnormality is detected.

"Risk stratification for future coronary events is a large focus of cardiovascular care for outpatients, and thus our findings for the predictive power of a carotid bruit can be useful," write Pickett et al.

In an editorial accompanying the study [2], Drs Victor Aboyans and Phillipe Lacroix (Dupuytren University Hospital, Limoges, France) note that the physical exam has lost some of its original value, particularly because other noninvasive methods have become available. "The higher accuracy of these noninvasive methods along with the dominant image culture shifted our diagnostic approach from physical examination toward an increasing need for imaging methods," they write.

The editorialists note that radiography, ultrasound, and other methods introduced to aid in diagnosis are used as prognostic markers, and the last gap to complete this circle would be to determine whether physical signs first used in diagnosis could also aid in determining a patient's prognosis. They point out that many of these other validated cardiovascular risk markers, such as coronary artery calcium screening, are often out of reach in the physician's office and are expensive. In developing countries, high-tech imaging is not available now or in the foreseeable future for aiding in disease prognosis.

Regarding the study by Pickett and colleagues, Aboyans and Lacroix write that one-third of patients had existing cardiovascular disease, raising questions about how the detection of a carotid bruit would alter secondary prevention. In addition, the prognostic value of a carotid bruit was not compared with risk scores for cardiovascular disease, and therefore the incremental value is unknown. Moreover, the presence of carotid bruit is low in subjects 45 years of age and older, about 4%, and while it increases with age, other clinical signs exist that could be of similar prognostic significance.

What is needed, they write, is a comparison between various clinical signs, like neck and groin auscultation, and vascular markers, such as heart rate, pulse pressure, or blood pressure, and these studies could be used to "narrow the indications of cardiovascular imaging techniques and make them more cost-effective in developed countries."