CORRESPONDENCE: LETTER TO THE EDITOR
Coronary Plaque Burden and Cardiovascular Risk Factors: Single-Point Versus Serial Assessment
Clemens von Birgelen, MD, PhD* and
Marc Hartmann, MD
* Medisch Spectrum Twente, Thoraxcentrum Twente, Cardiology Department, Haaksbergerstraat 55, 7513ER Enschede, the Netherlands (Email: von.birgelen{at}12move.nl).
In their interesting study, Nicholls et al. (1
) recently assessed in a large series of patients the relation between various cardiovascular risk factors and the amount of coronary plaque burden with (non-serial
) volumetric intravascular ultrasound (IVUS). In this set of high-quality data, male gender, diabetes mellitus, and a history of revascularization were the only predictors of the extent of plaque burden, whereas the established cardiovascular risk factor low-density lipoprotein cholesterol (LDL-C) showed no statistically significant relation to the amount of plaque burden (1
).
Our group serially assessed left main stems of patients with coronary artery disease treated by usual care with IVUS. Similar to the findings of Nicholls et al. (1
), at baseline (single-point observation
) we also found that patients with low versus high LDL-C levels had no difference in coronary plaque burden (2
). However, our patients with high LDL-C levels showed significantly more plaque progression during IVUS follow-up (serial observation
) (2
). Using these data, we were able to show for the first time a significant linear relation between LDL-C levels and coronary plaque progression as directly measured by IVUS (2
); later, this was confirmed by large pharmacological intervention trials with serial IVUS (3
).
The aforementioned pieces of evidence suggest that the extent of atherosclerotic plaque burden, as assessed at a single point in time, does not sufficiently predict the rate of plaque progression during follow-up. The extent of plaque burden can be in a balance between plaque progression and regression. In other words, plaques may be "progressors" despite a relatively small plaque burden, and plaques may be "regressors" despite a relatively great plaque burden. This underlies the fact that single-point observations are unable to characterize the "dynamic status" of coronary lesions.
Coronary remodeling (changes in total vessel size) may be partly responsible for the contradiction between the findings of single-point versus serial assessment when analyzing percent plaque burden. Plaque burden is in fact the relation between total vessel and plaque size: if plaque size remains unchanged but vessel size decreases ("negative remodeling"), the calculated percent plaque burden increases; and if total vessel size increases ("positive remodeling"), plaque burden decreases. Although the remodeling index shows a relatively close relationship with the subsequent direction of true serial remodeling (4
), we were unable to demonstrate a relation between plaque burden and changes in total vessel dimensions (i.e., serial remodeling) (5
), which underlies the relative independence of actual coronary remodeling from baseline plaque burden.
Finally, serial
observational ultrasound data suggest that coronary plaque progression by IVUS may be associated with increased cardiovascular risk (6
). We found that patients at the highest estimated cardiovascular risk, as derived from 3 established cardiovascular risk scores, showed the highest plaque progression rates; in addition, patients with greater plaque progression had significantly more actual cardiovascular events during follow-up (6
).
Thus, we believe that serial assessment of coronary plaques (progression–regression)—if possible with volumetric analyses (7
)—should be the "gold standard" when analyzing the relation between cardiovascular risk factors and coronary atherosclerosis.
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Footnotes
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Please note: Neil Weissman, MD, acted as guest editor.
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References
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1. Nicholls SJ, Tuzcu EM, Crowe T, et al. Relationship between cardiovascular risk factors and atherosclerotic disease burden measured by intravascular ultrasound J Am Coll Cardiol 2006;47:1967-1975.[Abstract/Free Full Text]2. von Birgelen C, Hartmann M, Mintz GS, Baumgart D, Schmermund A, Erbel R. Relation between progression and regression of atherosclerotic left main coronary artery disease and serum cholesterol levels as assessed with serial long-term ( 12 months) follow-up intravascular ultrasound Circulation 2003;108:2757-2762.[Abstract/Free Full Text] 3. Nissen SE, Nicholls SJ, Sipahi I, et al. ASTEROID Investigators Effect of very high-intensity statin therapy on regression of coronary atherosclerosis—the Asteriod trial JAMA 2006;295:1556-1565.[Abstract/Free Full Text] 4. von Birgelen C, Hartmann M, Mintz GS, et al. Remodeling index compared to actual vascular remodeling in atherosclerotic left main coronary arteries as assessed with long-term (12 months) serial intravascular ultrasound J Am Coll Cardiol 2006;47:1363-1368.[Abstract/Free Full Text] 5. Hartmann M, von Birgelen C, Mintz GS, Verhorst PMJ, Erbel R. Relation between baseline plaque burden and subsequent remodelling of atherosclerotic left main coronary arteries: a serial intravascular ultrasound study with long-term (12 months) follow-up Eur Heart J 2006May 22 [e-pub ahead of print]; doi: 10.1093/eurheartj/ehl034
). 6. von Birgelen C, Hartmann M, Mintz GS, et al. Relationship between cardiovascular risk as predicted by established risk scores versus plaque progression as measured by serial intravascular ultrasound in left main coronary arteries Circulation 2004;110:1579-1585.[Abstract/Free Full Text] 7. von Birgelen C, Slager CJ, Di Mario C, de Feyter PJ, Serruys PW. Volumetric intracoronary ultrasound: a new maximum confidence approach for the quantitative assessment of progression–regression of atherosclerosis? Atherosclerosis 1995;118(Suppl):S103-S113.[Web of Science][Medline]
Related Article
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Reply
- Stephen J. Nicholls, E. Murat Tuzcu, and Steven E. Nissen
J. Am. Coll. Cardiol. 2006 48: 1915-1916.
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