Background The presence and extent of coronary artery calcium (CAC) is an independent predictor of coronary heart disease (CHD) morbidity and mortality. Few studies have evaluated interactions or independent incremental risk for coronary and thoracic aortic calcification (TAC). The independent predictive value of TAC for CHD events is not well-established. Methods This study used risk factor and computed tomography scan data from 6,807 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). Using the same images for each participant, TAC and CAC were each computed using the Agatston method. The study subjects were free of incident CHD at entry into the study. Results The mean age of the study population (n=6807) was 62±10 years (47% males). At baseline, the prevalence of TAC and CAC was 28 % (1,904/6,809) and 50% (3393/6809), respectively. Over 4.5±0.9 years, a total of 232 participants (3.41%) had CHD events, of which 132 (1.94%) had a hard event (myocardial infarction, resuscitated cardiac arrest, or CHD death). There was a significant interaction between gender and TAC for CHD events (p<0.05). Specifically, in women, the risk of all CHD event was nearly 3-fold greater among those with any TAC (hazard ratio: 3.04, 95% CI; 1.60–5.76). After further adjustment for increasing CAC score, this risk was attenuated but remained robust (HR: 2.15, 95% CI: 1.10–4.17). Conversely, there was no significant association between TAC and incident CHD in men. In women, the likelihood ratio chi square statistics indicate that the addition of TAC contributed significantly to predicting incident CHD event above that provided by traditional risk factors alone (chi square= 12.44, p=0.0004) as well as risk factors + CAC scores (chi square= 5.33, p=0.02) . On the other hand, addition of TAC only contributed in the prediction of hard CHD events to traditional risk factors (chi-square=4.33, p=0.04) in women, without contributing to the model containing both risk factors and CAC scores (chi square=1.55, p=0.21). Conclusion Our study indicates that TAC is a significant predictor of future coronary events only in women, independent of CAC. On studies obtained for either cardiac or lung applications, determination of TAC may provide modest supplementary prognostic information in women with no extra cost or radiation.

Purpose Cardiac CT scans for the assessment of coronary calcium scores include approximately 70% of the lung volume and may be useful for the quantitative assessment of emphysema. The reproducibility of lung density measures from cardiac CTs and their validity compared to lung density measures from full-lung scans is unknown. Methods and Methods The Multi-Ethnic Study of Atherosclerosis (MESA) performed paired cardiac CT scans for 6,814 participants at baseline and at follow-up. The MESA-Lung Study assessed lung density measures in the lung fields of these cardiac scans, counting voxels below -910 HU as moderate-to-severe emphysema-like lung regions. We evaluated: 1) the reproducibility of lung density measures among 120 randomly selected participants, 2) the comparability of measures acquired on electron-beam CT (EBT) and multidetector CT (MDCT) scanners among 10 participants; and 3) the validity of these measures compared to full-lung scans among 42 participants. Limits of agreement were determined using Bland-Altman approaches. Results Percent emphysema measures from paired cardiac scans were highly correlated (r=0.92-0.95) with mean difference of -0.05% (95% limits of agreement: -8.3, 8.4%). Measures from EBT and MDCT scanners were comparable (mean difference -0.9%; 95% limits of agreement: -5.1, 3.3%). Percent emphysema measures from MDCT cardiac and MDCT full-lung scans were highly correlated (r=0.93) and demonstrated reasonable agreement (mean difference 2.2%; 95% limits of agreement: -9.2, 13.8%). Conclusion While full-lung imaging is preferred for the quantification of emphysema, the lung imaging from paired cardiac CTs provided a reproducible and valid quantitative assessment of emphysema in a population-based sample.