What Do We Know?

It comes as absolutely no surprise that the newest statistics released by the Centers for Disease Control and Prevention show that coronary artery disease (CAD) remains the number one killer of people in North America. And the culprit? Atherosclerotic plaques in the coronary arteries. But we know that atherosclerosis is a systemic arterial process; hence, it is well recognized that significant vulnerable plaques in the carotid vasculature can be a source of embolic strokes, with cerebrovascular disease being the fourth leading cause of death in the United States. What else do we know? We know that CAD can, in the vast majority of cases, be prevented by not smoking, by exercising at least 150 min per week, by not becoming overweight or obese, and by eating a healthy diet (i.e., as if you lived in the Greek isles or in the south of France). Medication and lifestyle choices can not only ameliorate risk factors for CAD, but once CAD is diagnosed, they can be part of the therapy to prevent myocardial infarctions.

What If?

What if we had an accurate, low-cost, reproducible, noninvasive test to tell us which patients do or do not have significant CAD? There is extensive literature pointing out the role of exercise stress testing in diagnosis and prognosis for CAD. Recently, coronary calcium scoring has become the go-to imaging test to determine potential significant coronary atherosclerotic burden, and it offers important prognostic information. So some would argue that we do have testing available. But what if we had a small, handheld ultrasound device that might tell us which patients have significant CAD and are at risk for its sequelae? More important, what if this device could be used wherever the patients are: in their doctors’ offices, in clinics, or even in emergency departments. This clearly might be able to help us identify those patients in whom appropriate interventions, such as angiography and other therapies, could be considered and, importantly, in which patients such approaches would be unnecessary. If this were the case, we clearly would be able to improve the quality of care for our individual patients.

What If?

What if we had an accurate, low-cost, reproducible, noninvasive test to tell us which patients do or do not have significant CAD? There is extensive literature pointing out the role of exercise stress testing in diagnosis and prognosis for CAD. Recently, coronary calcium scoring has become the go-to imaging test to determine potential significant coronary atherosclerotic burden, and it offers important prognostic information. So some would argue that we do have testing available. But what if we had a small, handheld ultrasound device that might tell us which patients have significant CAD and are at risk for its sequelae? More important, what if this device could be used wherever the patients are: in their doctors’ offices, in clinics, or even in emergency departments. This clearly might be able to help us identify those patients in whom appropriate interventions, such as angiography and other therapies, could be considered and, importantly, in which patients such approaches would be unnecessary. If this were the case, we clearly would be able to improve the quality of care for our individual patients.

So What Can We See by Looking?

In the present issue of JASE , we get a look at this kind of technology and the potential it offers. Johri et al. show the role that a focused vascular ultrasound (FOVUS) examination might play in detecting those who have, or do not have, significant CAD. These investigators looked at the ability of a cardiac sonographer who had not had extensive training in vascular ultrasound to use a small, linear, handheld transducer to evaluate the carotid artery bulbs very quickly and very simply in outpatients who were classified as being at low or intermediate risk for CAD but who for various reasons were undergoing coronary angiography. And what did they find? The presence of a carotid artery plaque in the bulb that had a maximum height of ≥1.5 mm had a good negative predictive value (77%) and high sensitivity (93%) for detecting those who had significant angiographically proven CAD. Adding the FOVUS examination to any form of exercise testing dramatically improved the negative predictive value and sensitivity of these tests. Importantly, it reclassified 34 of 50 patients (68%) who had negative stress testing results from low to high risk. The investigators emphasized that the FOVUS examination helps identify not only those who really do have significant CAD but, importantly, those who do not have significant CAD, thereby preventing unnecessary testing in this era of appropriate utilization and cost restraints.

Some Interesting Thoughts

Many have suggested that carotid ultrasound could have high incremental value and clinical utility as a cardiac risk screening examination. The emphasis of these complete examinations has been on their ability to determine percentage luminal narrowing and intima-media thickness, as a way to look at potential risk for cerebrovascular complications from carotid atherosclerosis as well as to determine potential systemic atherosclerotic risk. But the findings presented by Johri et al. suggest that a very simple and quick look for plaque in the carotid bulb may, in fact, be an excellent surrogate “biomarker” for significant CAD, meaning that a complete carotid ultrasound examination is unnecessary.

Equally striking in its implication is the fact that the FOVUS examination was performed by a cardiac sonographer without extensive training in vascular ultrasound. This sonographer was quickly able to interrogate the carotid bulb in both longitudinal and cross-sectional views, obtaining the important information about plaque presence and plaque height. This suggests that an individual could be quickly trained to scan the carotid bulb, even if that individual had little or no formal vascular ultrasound experience. Whether one who has no previous experience with cardiac ultrasound could be taught to do these scans or not is an important question that should be evaluated in the future.

For years, as a director of major noninvasive cardiac ultrasound laboratories, I was a strong proponent for allowing very experienced and certified cardiac sonographers and echocardiographers to develop their skills in performing and interpreting complete carotid vascular ultrasound examinations. This was clearly at a time before certification of physicians in vascular ultrasound was mandated. I felt then, as I do now, that having qualified echosonographers and echocardiographic physicians be able to offer excellent vascular carotid examinations in the noninvasive echocardiographic laboratory was appropriate for the level of services we would provide for patients referred to our laboratories. The report by Johri et al. stimulates us to think that there is an important role for sonographers to be able to perform a brief, simple FOVUS examination of the carotid bulb—an examination done at no cost, with minimal additional time—thereby giving important information about patients’ risk for significant CAD.

The use of a FOVUS examination to detect carotid bulb plaque and, thereby, to predict which patients might have significant CAD, is somewhat akin to a study by Abe et al. Those investigators showed that a commercially available, simple, pocket-sized echocardiographic instrument, one that did not have cardiac Doppler capability, could be used to rapidly tell, in patients being evaluated for systolic ejection murmurs, which ones might have severe aortic stenosis. By simply looking at the extent of aortic cusp separation, as visualized by these pocket-sized echocardiographic instruments, the investigators showed that handheld ultrasound was able to detect those patients who might well have significant aortic stenosis and, hence, could benefit from full cardiac ultrasound workup or other workup. So both the study by Johri et al. and the study by Abe et al. argue that focused ultrasound examinations can be used as an appropriate enhancement of our physical examination or workup of patients to detect those who are most likely to have or, in fact, not have cardiovascular disease.