Relationship between baseline coronary calcium score and demonstration of coronary artery stenoses during follow-up MESA (Multi-Ethnic Study of Atherosclerosis)

Abstract

Objectives: The MESA (Multi-Ethnic Study of Atherosclerosis) is a population-based study of 6,814 men and women. We sought to analyze the relationship between the extent of coronary artery calcium (CAC) at baseline and the severity of coronary stenoses in clinically indicated coronary angiography studies during follow-up.

Background: CAC is an established predictor of major cardiovascular events. Yet, the relationship between CAC and the distribution and severity of coronary artery stenoses has not been widely explored.

Methods: All MESA participants underwent noncontrast enhanced cardiac computed tomography during enrollment to determine baseline CAC. We analyzed 175 consecutive angiography reports from participants who underwent coronary catheterization for clinical indications during a median follow-up period of 18 months. The relationship between baseline CAC and the severity of coronary stenosis detected in coronary angiographies was determined.

Results: Baseline Agatston score was 0 in only 7 of 175 (4%) MESA participants who underwent invasive angiography during follow-up. When coronary arteries were studied separately, 13% to 18% of coronary arteries with >or=75% stenosis had 0 calcium mass scores at baseline. There was close association between baseline calcium mass score and the severity of stenosis in each of the coronary arteries (test for trend, p < 0.001). For example, mean calcium mass scores for <50%, 50% to 74%, and >or=75% stenosis in the left anterior descending coronary artery were 105.1 mg, 157.2 mg, and 302.2 mg, respectively (p < 0.001). Finally, there was a direct relationship between the total Agatston Score at baseline and the number of diseased vessels (test for trend, p < 0.001).

Conclusions: The majority of patients with clinically indicated coronary angiography during follow-up had detectable coronary calcification at baseline. Although there is a significant relationship between the extent of calcification and mean degree of stenosis in individual coronary vessels, 16% of the coronary arteries with significant stenoses had no calcification at baseline.

Figure 1. Relationship between calcium score and the severity of coronary artery stenosis

Calcium mass score as a measure of coronary calcification in each of the coronary arteries with different levels of stenosis. White bars indicate 0–49% stenosis, yellow bars 50–74% and blue bars indicate ≥75% stenosis. (Exception: for the left main artery the corresponding categories are 0–24%, 25–49% and ≥50% stenosis). Standard error bars are shown. Test for trend across the different stenosis categories were significant for each artery (p<0.05 for the LM, p<0.001 in each of the other arteries). Analysis of variance on the log- transformed values of CACP scores was used to test for trend. LM- left main, LAD- left anterior descending, LCX- left circumflex, RCA- right coronary artery.

Figure 2

2A: Distribution of LAD stenosis with increasing LAD CACP mass quartiles 2B: Distribution of LCX stenosis with increasing LCX CACP mass quartiles. 2C: Distribution of RCA stenosis with increasing RCA CACP mass quartiles 2D: Distribution of LM stenosis with increasing LM CACP mass quartiles. The distribution of the severity of coronary stenosis across quartiles of the coronary calcium score in the LAD (2A), LCX (Figure 2B), RCA (2C) and left main coronary artery (2D). In figures 2A-C, the blue portion indicates ≥75% stenosis, yellow indicates 50–74% stenosis and the white part of the bars indicates 0–49% stenosis. In Figure 2D, the blue portion indicates ≥50% stenosis, the yellow portion 25–49% stenosis and the white part of the bars 0–24% stenosis. For all arteries, the Chi square test for association between CACP quartile and % stenosis group was significant (p<0.001 for each). Ranges of CACP scores for each quartile: LAD: I 0 to 0; II. 0.9 to 86.7; III 87.2 to 287.8; IV 290.7 yo 1368.4 LCX: I 0 to 0; II 1.6 to 19.7; III 24.5 to 174.8; IV 176.0 to 1884.8 RCA: I 0 to 0; II 1.2 to 13.6; III 13.6 to 121.3; IV 127.5 to 1799.4 LM: I. 0 to 0; II 0 to 0.78; III 0.78 to 3.7; IV. 4.7 to 543.5.

Figure 2

2A: Distribution of LAD stenosis with increasing LAD CACP mass quartiles 2B: Distribution of LCX stenosis with increasing LCX CACP mass quartiles. 2C: Distribution of RCA stenosis with increasing RCA CACP mass quartiles 2D: Distribution of LM stenosis with increasing LM CACP mass quartiles. The distribution of the severity of coronary stenosis across quartiles of the coronary calcium score in the LAD (2A), LCX (Figure 2B), RCA (2C) and left main coronary artery (2D). In figures 2A-C, the blue portion indicates ≥75% stenosis, yellow indicates 50–74% stenosis and the white part of the bars indicates 0–49% stenosis. In Figure 2D, the blue portion indicates ≥50% stenosis, the yellow portion 25–49% stenosis and the white part of the bars 0–24% stenosis. For all arteries, the Chi square test for association between CACP quartile and % stenosis group was significant (p<0.001 for each). Ranges of CACP scores for each quartile: LAD: I 0 to 0; II. 0.9 to 86.7; III 87.2 to 287.8; IV 290.7 yo 1368.4 LCX: I 0 to 0; II 1.6 to 19.7; III 24.5 to 174.8; IV 176.0 to 1884.8 RCA: I 0 to 0; II 1.2 to 13.6; III 13.6 to 121.3; IV 127.5 to 1799.4 LM: I. 0 to 0; II 0 to 0.78; III 0.78 to 3.7; IV. 4.7 to 543.5.

Figure 2

2A: Distribution of LAD stenosis with increasing LAD CACP mass quartiles 2B: Distribution of LCX stenosis with increasing LCX CACP mass quartiles. 2C: Distribution of RCA stenosis with increasing RCA CACP mass quartiles 2D: Distribution of LM stenosis with increasing LM CACP mass quartiles. The distribution of the severity of coronary stenosis across quartiles of the coronary calcium score in the LAD (2A), LCX (Figure 2B), RCA (2C) and left main coronary artery (2D). In figures 2A-C, the blue portion indicates ≥75% stenosis, yellow indicates 50–74% stenosis and the white part of the bars indicates 0–49% stenosis. In Figure 2D, the blue portion indicates ≥50% stenosis, the yellow portion 25–49% stenosis and the white part of the bars 0–24% stenosis. For all arteries, the Chi square test for association between CACP quartile and % stenosis group was significant (p<0.001 for each). Ranges of CACP scores for each quartile: LAD: I 0 to 0; II. 0.9 to 86.7; III 87.2 to 287.8; IV 290.7 yo 1368.4 LCX: I 0 to 0; II 1.6 to 19.7; III 24.5 to 174.8; IV 176.0 to 1884.8 RCA: I 0 to 0; II 1.2 to 13.6; III 13.6 to 121.3; IV 127.5 to 1799.4 LM: I. 0 to 0; II 0 to 0.78; III 0.78 to 3.7; IV. 4.7 to 543.5.

Figure 2

2A: Distribution of LAD stenosis with increasing LAD CACP mass quartiles 2B: Distribution of LCX stenosis with increasing LCX CACP mass quartiles. 2C: Distribution of RCA stenosis with increasing RCA CACP mass quartiles 2D: Distribution of LM stenosis with increasing LM CACP mass quartiles. The distribution of the severity of coronary stenosis across quartiles of the coronary calcium score in the LAD (2A), LCX (Figure 2B), RCA (2C) and left main coronary artery (2D). In figures 2A-C, the blue portion indicates ≥75% stenosis, yellow indicates 50–74% stenosis and the white part of the bars indicates 0–49% stenosis. In Figure 2D, the blue portion indicates ≥50% stenosis, the yellow portion 25–49% stenosis and the white part of the bars 0–24% stenosis. For all arteries, the Chi square test for association between CACP quartile and % stenosis group was significant (p<0.001 for each). Ranges of CACP scores for each quartile: LAD: I 0 to 0; II. 0.9 to 86.7; III 87.2 to 287.8; IV 290.7 yo 1368.4 LCX: I 0 to 0; II 1.6 to 19.7; III 24.5 to 174.8; IV 176.0 to 1884.8 RCA: I 0 to 0; II 1.2 to 13.6; III 13.6 to 121.3; IV 127.5 to 1799.4 LM: I. 0 to 0; II 0 to 0.78; III 0.78 to 3.7; IV. 4.7 to 543.5.

Figure 3. Relationship between number of diseased coronaries and Agatston score

Agatston calcium score (phantom adjusted) in individuals with non-significant coronary artery disease and in those with one, two, three vessel disease and left main coronary artery disease. Significant vessel disease is defined as ≥ 50% stenosis in the left main artery or ≥ 75 stenosis in the LAD, LCX or RCA coronary arteries. Standard error bars are shown. The test for trend (ANOVA on log transformed CACP) among the four different groups was highly significant (p<0.001).

Figure 4. Distribution of diseased coronaries with increasing Agatston score

The distribution of coronary artery disease among individuals with different Agatston Scores (<100, 100–199, 200–299, 300–399 and ≥400 units). The white portions indicate non-significant CAD, while the gray, blue, yellow and black portions indicate one, two, three vessel disease and left main disease, respectively. The Chi square test for association between calcium score category and extent of disease was highly significant (p<0.001).