Continuous multilead ST-segment monitoring should be a part of the clinical routine.

laboratories that have sought to use the anatomical and pathological rationale that I have suggested above should drive the carotid intima–media thickness protocol, I believe the use of the composite measure would be strongly confirmed. Finally, when considering what segments should be studied in evaluating the effectiveness of a drug in retarding the progression of carotid intima–media thickness (and presumably atherosclerosis), a similar argument can be made. A number of very successful multicentre clinical trials have used a carotid intima–media thickness outcome variable including data from all three anatomical segments that were acquired from a complete circumferential scan of each carotid artery. In principle, a drug may well be expected to have different effects on retarding progression of carotid intima–media thickness in different anatomical segments. Thus limiting studies to the common carotid artery only (far wall only even) or to only one of the other two segments accessible to ultrasonic imaging may do a relatively poor job of determining if a drug is effective. Drugs that are truly effective overall may be found to be ineffective due to limiting the study to only one of the three accessible sites. Furthermore, effectiveness of a drug in the common carotid artery alone may be due to dilatory effects of the drug on the arterial diameter and be incorrectly interpreted as effective in retarding progression of intima–media thickness. In summary, from a scientific perspective, it makes good sense to measure carotid intima–media thickness in all three segments accessible to high resolution B-mode ultrasound. It requires developing greater skill within and more effort from the individuals charged with obtaining the B-mode images of artery walls needed to make these measurements. This will require more time to train and certify these individuals. If one does not take this approach, one will do a relatively poor job of characterizing the level of risk within an individual as well as be led to incorrect evaluations of therapeutic agents. One could reasonably say that too many of our diagnostic tests with medical ultrasound are not done in a particularly reliable manner. How often do we even have a valid quality control/quality assurance programme in place to really know the reliability of our tests? We owe it to the potential of carotid intima–media thickness that it not go the way of other diagnostic tests due to a lack of resolve to do it the right way and to commit the necessary level of resources to the task. W. A. RILEY Wake Forest University School of Medicine, Winston-Salem, NC, U.S.A.