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(Circulation. 2000;102:e20.)
© 2000 American Heart Association, Inc.

Circulation Electronic Pages

Coronary Calcium Does Not Accurately Predict Near-Term Future Coronary Events in High-Risk Adults

Warren R. Janowitz, MD

Miami Cardiac and Vascular Institute Baptist Hospital of Miami, 8900 North Kendall Drive, Miami, FL 33176-2197, Warren.Janowitz@worldnet.att.net

	Introduction

 
To the Editor:

The article by Detrano et al¹ concerning the predictive value of coronary artery calcium contains fundamental flaws in methodology that may invalidate their conclusions.

Their protocol differs significantly from the original protocol, which was designed to be sensitive to the presence of small amounts of calcium and to accurately reflect the quantity of calcium present.² Multiple studies have shown that these goals were met surprisingly well.³ The differences in protocol can account for the lack of discriminative power found in their article, without criticizing the high-risk composition of their study group.⁴ Using 6-mm-thick slices, instead of 3 mm, increases the volume averaging inherent in CT scanning. Small calcified lesions may not meet the density threshold criteria for a calcified lesion with 6-mm-thick slices. There is also a 2-fold decrease in the number of lesions seen in 6-mm slices versus 3-mm slices, which decreases the calcium score by a factor of 2.

The use of an 8.16 mm³ threshold for defining a calcified lesion also significantly reduces sensitivity. This is 5x the original threshold. Lesions, which could have a potential contribution of 10 to the total calcium, could have a score of 0 with Detrano et al’s modifications. In combination with increased volume averaging, this higher volume threshold will have an even greater effect. It seems that a total calcium score in the range of 80 to 160 defines a high-risk group.^{5 6} The potential magnitude of score reduction using Detrano et al’s modifications are of the same . . . [Full Text of this Article]

Robert C. Detrano, MD, PhD

Division of Cardiology Department of Medicine, Harbor-UCLA Medical Center and Saint John’s Cardiovascular Research, 1124 West Carson Street, Building RB2, Torrance, CA 90502-2064, detrano@harbor4.humc.edu

Nathan D. Wong, PhD; Terence M. Doherty, BA; Robert M. Shavelle, PhD; Weiyi Tang, MD; Leonard E. Ginzton, MD; Matthew J. Budoff, MD; Kenneth A. Narahara, MD