John Postley MD
Just recently a 62 year old athletic financial executive dropped dead while exercising on his treadmill. The shock waves reverberated throughout the community. How could this happen to a man in such good health who obviously had the best of care. Cardiovascular disease is the leading cause of death and disability in the United States. There are over 780,000 first heart attacks every year and they have a 34% death rate in the first year. There are over 600,000 first strokes every year as well. Only half of these events occur in persons in whom the risk factors of high blood pressure, cholesterol, smoking and diabetes will predict their occurrence. The rest occur in people who believe they are in good health and have been told so by their physicians.
How can this happen? The traditional risk factor formulas are heavily weighted by age and being a male. If you are a female and younger, you will be missed in terms of risk analysis. Furthermore, while the risk factors of blood pressure and cholesterol, diabetes and smoking are important, a comprehensive study published earlier this year shows that together they represent about half of the risk in American’s cardiovascular events (strokes AND heart attacks).
What are the other causes? We simply do not know. There are hereditary causes but heart disease is not like having blue eyes or brown eyes in which you can trace a single gene from generation to generation. The genetics of heart disease is polygenic. It involves lots of different genes, some of which we know but most are still to be discovered. In addition, it may be the specific combination of genes which determines the risk, so you could have 2 “bad” genes but they would not be a problem unless you also acquired a third.
The obvious solution to this problem is to go beyond the known risk factors and try to assess the arteries directly. This is the concept behind the cardiac stress test. You exercise the heart to the point where if there is a narrowing of an artery you will see a change in the electrocardiogram or the echocardiogram or the nuclear isotope pattern. The main problem with this is that the test requires a 80 to 90% narrowing of an artery to produce an abnormality but you need only a 30% narrowing to clot and kill you.
There are 2 non-invasive ways of judging cardiovascular risk. You can do a CT scan of the heart. This has been shown for years to be an effective way of identifying many people who are at risk but missed by the traditional risk formulas. It does require radiation so it is not something you would want to do frequently and it is more successful in picking up advanced disease since the cholesterol plaques in the heart arteries have to become calcified to be seen on the CT scan. It tends to be more useful in older males.
The other approach is to look at the arteries in the neck and groin with an ultrasound machine: the same kind of machine that the obstetrician uses to see babies in the womb. This is clearly a no risk procedure but it is also much more sensitive since we can see small blips which may be only 2 mm in thickness. Studies have shown that the combination of neck and groin ultrasound is a most sensitive way of identifying people with few or no risk factors who really have arterial disease that will trigger strokes and heart attacks. Such patients can be identified 10 years prior to a stroke or heart attack. However, it is necessary to do both neck and groin evaluation since we and others have confirmed the substantial number of people missed if you examine only the neck arteries.
The physicians at NYP have been in the forefront of the development of ultrasound screening for cardiovascular risk. In papers published in 2009 and newly accepted for publication in major cardiovascular journals, we have shown that our non-invasive ultrasound screening can identify people at serious risk for cardiovascular disease but missed by the traditional risk formulas. Our work has recently been confirmed by a large international study published in a major journal of the American Heart Association. Unfortunately, as a new use of proven technology, there is no insurance coverage for this test but is fairly priced at $275.
American Heart Association. 2012 heart and stroke statistical update. Available at: http://www.americanheart.org
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Fernandez-Friera L et al. Prevalence, vascular distribution and multi-territorial extent of subclinical atherosclerosis in a middle-aged cohort: The PESA Study. Circulation 2015; 131:2104-2113
Postley JE et al. Prevalence and distribution of sub-clinical atherosclerosis by screening vascular ultrasound in low and intermediate risk adults: The New York Physicians Study. J Am SocEchocardiogr 2009; 22:1145-1151
Postley JE et al Identification by ultrasound evaluation of the carotid and femoral arteries of high-risk subjects missed by three validated cardiovascular disease risk algorithms. Am J Cardiol, in press