LDL-cholesterol predicts negative coronary artery remodelling in diabetic patients: an intravascular ultrasound study

We read with great interest the article entitled ‘LDL-cholesterol predicts negative coronary artery remodelling in diabetic patients: an intravascular ultrasound study’.1 A major finding of this study is the high frequency (72%) of negative remodelling (i.e. a decrease in total vessel cross-sectional area in response to development of an atherosclerotic plaque) in their cohort of diabetic patients. We think that several shortcomings in the methods could have contributed to this finding. In this study, all of the lesions used in the remodelling analyses were located in a coronary artery that had undergone stenting right before intravascular ultrasound imaging. These lesions had to be at least 10 mm distal or proximal to the stented segment. Negative remodelling was defined as a lesion external elastic membrane (EEM) area less than proximal reference EEM area, and the proximal reference site was chosen within 10 mm proximal to the lesion. Thus, in the case of lesions that were about 10 mm distal to the stented segment, the reference site would be very close (and possibly within) to the distal edge of the stent, which could be artificially dilated due to pre-dilatations, stent implantation, and post-dilatations. This would lead to an overestimation in the frequency negative remodelling. Moreover, defining remodelling using only a proximal reference does not take the normal vessel tapering into account and can also overestimate negative remodelling. However, using a definition of remodelling that includes not only the proximal but also the distal reference site can overcome this limitation and can change the results. Indeed, in one study that used both proximal and distal reference sites, in which the lesions were imaged before intervention, the frequency of negative remodelling in diabetic patients was reported to be <30%.2 Similarly, using another definition of remodelling that does not incorporate any measurements of the reference sites, positive remodelling was found to be the predominant remodelling behaviour in diabetics.3 According to the methods of the current report, the investigators measured EEM areas of not only the proximal, but also of the distal reference sites. However, data regarding the distal references are not reported. Additionally, the slopes of the regression lines of the second and third panels of Figure 3 should have negative values due to the inverse relationship between the parameters.