CORRESPONDENCE: LETTER TO THE EDITOR
Reply
Joanne D. Schuijf, PhD*,
Maureen M. Henneman, PhD, MD and
Jeroen J. Bax, PhD, MD
* Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, Leiden, Zuid-Holland 2333 ZA, the Netherlands (Email: j.d.schuijf{at}lumc.nl).
We thank Drs. Li, Sadat, and Gillard for their interest in our article on plaque characteristics on multislice computed tomography coronary angiography (MSCTA) versus coronary calcium score (CCS) in patients presenting with suspected acute coronary syndrome (1). The authors raise the possibility that not the total extent of calcium but rather its location within the atherosclerotic plaque is an important determinant of vulnerability. Indeed, the authors have previously demonstrated that while calcifications within the lipid core may stabilize the lesion, the presence of calcifications in the thin fibrous cap may in fact result in high stress and increased likelihood of rupture (2). Accordingly the authors suggest that integration of calcium location in the CCS may improve prediction of future cardiovascular events. Unfortunately, only calcified tissue is recognized on CCS. In contrast, other plaque components are not visualized, and as a result, it remains impossible to differentiate between calcium located in the thin fibrous cap or elsewhere in the lesion. Moreover, it is likely that precisely these small calcified deposits in the thin fibrous cap cannot even be identified during CCS or MSCTA because of the limited resolution of the technique. Indeed, previous comparison of plaque observations between MSCTA and virtual histology intravascular ultrasound showed that plaques deemed to be completely noncalcified on MSCTA still contained some small amount of calcium, albeit only very limited (3). Accordingly, small calcium deposits that potentially predispose the lesion to increased vulnerability may not always be detectable during CCS. Although in the general population with stable coronary artery disease, the presence of noncalcified tissue and small calcium deposits will coincide with larger calcifications and thus evidence of calcium on CCS, this phenomenon may not be the case in younger patients or in patients presenting with suspected acute coronary syndromes (1). Accordingly, for these patients caution remains warranted, as the observation of only minor or even no calcifications during CCS may not reliably exclude the presence of substantial atherosclerosis or potentially vulnerable lesions.
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1. Henneman MM, Schuijf JD, Pundziute G, et al. Noninvasive evaluation with multislice computed tomography in suspected acute coronary syndrome: plaque morphology on multislice computed tomography versus coronary calcium score J Am Coll Cardiol 2008;52:216-222.[Abstract/Free Full Text]2. Li ZY, Howarth S, Tang T, Graves M, King-Im J, Gillard JH. Does calcium deposition play a role in the stability of atheroma?. Location may be the key. Cerebrovasc Dis 2007;24:452-459.[CrossRef][Web of Science][Medline] 3. Pundziute G, Schuijf JD, Jukema JW, et al. Head-to-head comparison of coronary plaque evaluation between multi-slice computed tomography and intravascular ultrasound radiofrequency data analysis J Am Coll Cardiol Intv 2008;1:176-182.[Abstract/Free Full Text]
Related Article
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Coronary Calcium Scoring: Calcium Location Needs to Be Integrated!
- Zhi-Yong Li, Umar Sadat, and Jonathan H. Gillard
J. Am. Coll. Cardiol. 2009 54: 745.
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