Distribution, size, shape, growth potential and extent of abdominal aortic calcified deposits predict mortality in postmenopausal women

Abstract

Background: Aortic calcification is a major risk factor for death from cardiovascular disease. We investigated the relationship between mortality and the composite markers of number, size, morphology and distribution of calcified plaques in the lumbar aorta.

Methods: 308 postmenopausal women aged 48-76 were followed for 8.3 ± 0.3 years, with deaths related to cardiovascular disease, cancer, or other causes being recorded. From lumbar X-rays at baseline the number (NCD), size, morphology and distribution of aortic calcification lesions were scored and combined into one Morphological Atherosclerotic Calcification Distribution (MACD) index. The hazard ratio for mortality was calculated for the MACD and for three other commonly used predictors: the EU SCORE card, the Framingham Coronary Heart Disease Risk Score (Framingham score), and the gold standard Aortic Calcification Severity score (AC24) developed from the Framingham Heart Study cohorts.

Results: All four scoring systems showed increasing age, smoking, and raised triglyceride levels were the main predictors of mortality after adjustment for all other metabolic and physical parameters. The SCORE card and the Framingham score resulted in a mortality hazard ratio increase per standard deviation (HR/SD) of 1.8 (1.51-2.13) and 2.6 (1.87-3.71), respectively. Of the morphological x-ray based measures, NCD revealed a HR/SD >2 adjusted for SCORE/Framingham. The MACD index scoring the distribution, size, morphology and number of lesions revealed the best predictive power for identification of patients at risk of mortality, with a hazard ratio of 15.6 (p < 0.001) for the 10% at greatest risk of death.

Conclusions: This study shows that it is not just the extent of aortic calcification that predicts risk of mortality, but also the distribution, shape and size of calcified lesions. The MACD index may provide a more sensitive predictor of mortality from aortic calcification than the commonly used AC24 and SCORE/Framingham point card systems.

Figure 1

Calcification Annotations. Lateral lumbar X-ray with calcifications in the lower region without (a) and with (b) computer-mediated annotations performed by radiologist.

Figure 2

For a given amount of calcified tissue, one can see schematically how the AC24, the NCD and the MACD can be influenced differently by variations in calcification morphology and distribution.

Figure 3

Of 557 postmenopausal women who completed an 8.5 year follow-up study, 55% of those alive at follow-up and 55% of those who were deceased had useful X-rays with the full abdominal aorta visible in a single x-ray. Thus, the study population included in this analysis consisted of a total of 308 women: 256 survivors and 52 deceased.

Figure 4

Odds ratio of death in the CVD and cancer group who were assessed as being in the 10% at greatest risk of mortality, versus survival in the remaining subjects. Significance of difference is indicated as * for p < 0.05, ** for p < 0.01, *** for p < 0.001 using the likelihood ratio of appropriately combined logistic regression models.