(Stroke. 2001;32:2443.)
© 2001 American Heart Association, Inc.
Letters to the Editor |
IMT for the Elderly?
Southern California Prevention and Research Center, Encino, California
To the Editor:
I would like to respond to an article published in a recent issue of Stroke, entitled "Is Carotid Intima-Media Thickness Useful in Cardiovascular Disease Risk Assessment?"1
The title of the article caught my eye because my profession involves extensive use of carotid intima-media thickness (CIMT) for detection of atherosclerosis. However, I was surprised that the title did not reflect the misleading nature of the article, and it appears to refute the authors’ earlier published works.2
The title of the article suggests that certain cardiovascular risks were compared with assessment of CIMT. The authors of this article concluded that as a screening tool, CIMT does not represent a substantial increase in the predictive value for cardiovascular events. Moreover, there was an inference that CIMT cannot be used alone as a screening tool. I must completely disagree. The article described the Rotterdam Study, in which investigators used CIMT as a screening tool in an elderly population. This was a select population that would have additional risk factors present. The question should have been raised as to whether exclusive use of CIMT in a younger population with risk factors is able to identify the presence of cardiovascular disease in its earliest stages. Even comparing two distinct population groups would yield a more meaningful result. CIMT is not appropriate for screening when the patient would have known cardiovascular disease risk factors in development. The key to controlling the disease is prevention, rather than dealing with it after it has progressed to riskier stages. A typical screening setting is for new patient discovery, and the methodology for screening was not optimal here. Unlike other screening methods, the purpose of CIMT is to look at the disease itself, instead of examining the risk factors. Risk factors are often arbitrarily selected by the investigator out of a pool of sometimes more that 246 suggested factors in every patient.3 In a different Netherlands study, a major risk factor like elevated cholesterol levels has been demonstrated by Sijbrands et al4 not to limit normal lifespan in 40% of the cases studied. Would this imply that measurement and interpretation of a risk factor is not all that relevant, but viewing the disease itself would be? The well-established statements by the American Heart Association and American College of Cardiology clearly indicate the value of CIMT alone as a predictor of cardiovascular and cerebrovascular events.5 This article gives the misleading impression that the technique of measurement of CIMT used in the Rotterdam Study is widely used. This important point was overlooked by the authors. The procedure described using calipers is clearly outdated; so is the aggregate maximum measurement of the IMT. Our group uses carotid IMT (IMTHeartScan) to screen different populations with a proprietary edge contour detection technique (ARTIS, Prevention Concepts Inc) in a screening setting, as well as a risk factor management setting. Our procedure allows us to predict with a high degree of confidence both an absolute and relative risk of cardiovascular complication in ethnically diverse population groups.6
In short, the eye-catching title does not cover the content of the article and disagrees with both current practice of this unique tool in cardiovascular management. Utilization of modern CIMT for screening in the appropriate population is a more effective tool than other methods for detecting the presence of cardiovascular disease in its earliest stages. This gives better opportunity for treatment and possible reversal of cardiac disease. I would suggest that the authors review more current methods for utilizing CIMT as a screening tool in cardiovascular disease detection. We remain confident that our ounce of prevention is worth a pound of cure.
References
1.
Del Sol AI, Moons KGM, Hollander M, Hofman A, Koudstaal PJ, Grobbee DE, Breteler MMB, Witteman JCM, Bots ML. Is carotid intima-media thickness useful in cardiovascular disease risk assessment? The Rotterdam Study. Stroke. 2001; 32: 1532–1538.
2.
Bots ML, Hoes AW, Koudstaal PJ, Hofman A, Grobbee DE. Common carotid intima-media thickness and risk of stroke and myocardial infarction: the Rotterdam Study. Circulation. 1997; 96: 1432–1437.
3. Hopkins PN, Williams RR. A survey of 246 suggested coronary risk factors. Atherosclerosis. 1981; 40: 1–52.[Medline] [Order article via Infotrieve]
4.
Sijbrands EJ, Westerdorp RGJ, Defesche JC, de Meier PHEM, Smelt AHM, Kastelein JJP. Mortality over two centuries in large pedigree with familial hypercholesterolaemia: a family tree mortality study. BMJ. 2001; 322: 1019.
5.
Greenland P, Abrams J, Aurigemma GP, Bond MG, Clark LT, Criqui MH, Crouse III, JR, Friedman L, Fuster V, Herrington DM, Kuller LH, Ridker PM, Roberts WC, Stanford W, Stone N, Swan J, Taubert KA, Wexler L. Prevention V, beyond secondary prevention: identifying the high-risk patient for primary prevention: noninvasive tests of atherosclerotic burden. Circulation. 2000; 101: e16–e22.
6. Barth JD. Which tools are in your cardiac workshop? Carotid ultrasound, endothelial function, and magnetic resonance imaging. Am J Cardiol. 2001; 87: 8A–14A.[Medline] [Order article via Infotrieve]
Response
Our article1 on the usefulness of carotid intima-media thickness measurements in cardiovascular risk assessment concluded that in a general population aged 55 years or older, when information on established risk factors (medical history, smoking, blood pressure, cholesterol, and body mass index) is available, the measurement of CIMT does not add substantially in distinguishing high-risk from low-risk patients. When, however, only age, sex, and CIMT were presented, there was a considerable increase in the diagnostic ability of the model. We agree with Dr Barth that our data pertain to subjects 55 years or older, and it may be different in younger populations and in high-risk populations.2 We disagree, however, that such measurements have no value in patients in which disease has progressed to some extent. Even in those at higher risk of coronary heart disease it may be of great importance to be able to identify those who are at a relative higher risk compared with those at a relative lower risk in order to target treatment.2
Instead of an arbitrary selection out of 246 risk factors, as Dr Barth suggested, our selection of established risk factors was based on the ability for a general practitioner to easily obtain that information, since in the Netherlands the general practitioner is usually the first line of the medical circuit to contact. The focus of our study was to evaluate the added value of the CIMT measurement when added to easily obtainable risk factors.
With respect to the CIMT measurement as performed in the Rotterdam Study, Dr Barth is of the opinion that we used an outdated measurement technique and that an aggregate maximum measurement of CIMT is also outdated. We would like to point out that the CIMT measurement technique used in the Rotterdam study is based on manual tracing over a 10-mm segment as well as on an automated edge technique that has been shown to be state of the art and is used in trials and population-based studies.3–5 Furthermore, we disagree with the "outdatedness" of aggregate measures. Clearly, the far wall of the common carotid is perhaps easier to measure and may yield a high reproducibility, but the aggregate measures reflect the entire carotid atherosclerosis burden and are and will remain a major outcome in trials.6–8
Finally, our CIMT measurement predicts future disease in a magnitude similar to that in other population-based studies that use either manual tracings or automated edge detection tracing.9–13
References
1. Iglesias del Sol A, Moons KGM, Hollander M, Hofman A, Breteler MMB, Koudstaal PJ, Grobbee DE, Witteman JCM, Bots ML. Is carotid intima-media thickness useful in cardiovascular disease risk assessment? The Rotterdam Study. Stroke. 2001; 32: 1532–1528.
2.
Simons PCG, Algra A, Bots ML, Grobbee DE, Graaf Y van der, for the SMART Study Group. Common carotid intima-media thickness and arterial stiffness. Indicators of cardiovascular risk in high-risk patients. The SMART study (second Manifestations of ARTerial disease). Circulation. 1999; 100: 951–957.
3. Stensland-Bugge E, Bonaa KH, Joakimsen O. Age and sex differences in the relationship between inherited and lifestyle risk factors and subclinical carotid atherosclerosis: the Tromso study. Atherosclerosis. 2001; 154: 437–448.[Medline] [Order article via Infotrieve]
4. Liang Q, Wendelhag I, Wikstrand J, Gustavsson T. A multiscale 2dynamic programming procedure for boundary detection in ultrasonic artery images. IEEE Trans Med Imaging. 2000; 19: 127–142.[Medline] [Order article via Infotrieve]
5.
Hedblad B, Wikstrand J, Janzon L, Wedel H, Berglund G. Low-dose metoprolol CR/XL and fluvastatin slow progression of carotid intima-media thickness: Main results from the Beta-Blocker Cholesterol-Lowering Asymptomatic Plaque Study (BCAPS). Circulation. 2001; 103: 1721–1726.
6.
Pitt B, Byington RP, Furberg CD, Hunninghake DB, Mancini GB, Miller ME, Riley W, for The PREVENT Investigator. Effect of amiodipine on the progression of atherosclerosis and the occurrence of events. Circulation. 2000; 102: 1503–1510.
7. Bots ML, Evans G, Meijer R, Paskett E, Grobbee DE, for the OPAL investigators. The osteoporosis prevention and arterial effects of Tibolone (OPAL) study: rationale, design and baseline characteristics.In: Program and abstracts of the4th International Symposium on Women’s Health and Menopause, May 19–23, 2001; Washington, DC. Abstract.
8.
Chambless LE, Heiss G, Folsom AR, Rosamond W, Szklo M, Sharrett AR, Clegg LX. Association of coronary heart disease incidence with carotid arterial wall thickness and major risk factors: the Atherosclerosis Risk in Communities (ARIC) Study, 1987-1993. Am J Epidemiol. 1997; 146: 483–494.
9. Bots ML, Hoes AW, Koudstaal PJ, Hofman A, Grobbee DE. Common carotid intima-media thickness and risk of stroke and myocardial infarction: the Rotterdam Study. Circulation. 1997; 96: 1432–1437.
10.
O’Leary DH, Polak JF, Kronmal RA, Manolio TA, Burke GL, Wolfson SK, for the cardiovascular Health Collaborative research Group. Carotid intima and media thickness as a risk factor for myocardial infarction and stroke in older subjects. N Engl J Med. 1999; 340: 14–22.
11.
Chambles LE; Folsom AR: Clegg LX, Sharett AR, Shahar E, Nieto FJ, Rosamond WD, Evans G. Carotid wall thickness is predictive of incident clinical stroke: the Atherosclerosis Risk in Communities (ARIC) study. Am J Epidemiol. 2000; 151: 478–487.
12.
Hodis HN, Mack WJ, LaBree L, Selzer RH, Liu C, Liu C, Azen SP. The role of carotid arterial intima-media thickness in predicting clinical coronary events. Ann Intern Med. 1998; 128: 262–269;.150:371–379.
13.
Touboul PJ, Elbaz A, Koller C, Lucas C, Adrai V, Chedru F, Amarenco P. Common carotid artery intima-media thickness and brain infarction: the Etude du Profil Genetique de l’Infarctus Cerebral (GENIC) case-control study. The GENIC Investigators. Circulation. 2000; 102: 313–318.
This article has been cited by other articles:
 |
|
 |
|
  J. D. Barth and C. K. Roberts Carotid intima-media thickness and coronary atherosclerosis: weak or strong relations? Eur. Heart J., October 2, 2007; 28(20): 2552 - 2552. [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||