Background

Nonalcoholic fatty liver disease (NAFLD) is associated with an increased risk of atherosclerotic cardiovascular disease (ASCVD) events; thus, a diagnostic approach to help identify NAFLD patients at high risk is needed. In this study, we hypothesized that coronary artery calcium (CAC) screening could help stratify the risk of ASCVD events in participants with suspected nonalcoholic hepatic steatosis.

Methods

A total of 713 participants with suspected nonalcoholic hepatic steatosis without previous cardiovascular events from the Multi-Ethnic Study of Atherosclerosis (MESA) were followed for the occurrence of incident ASCVD. Nonalcoholic hepatic steatosis was defined using nonenhanced computed tomography and liver/spleen attenuation ratio <1. Cox proportional hazards regression models were used to estimate hazard ratios (HR). C-statistics and areas under the time-dependent receiver operating characteristic curves (tAUC) were used to compare incremental contributions of CAC score when added to the clinical risk factors.

Results

In multivariable analyses, CAC score was found to be independently associated with incident ASCVD (HR = 1.33, 95% CI = 1.22-1.44, P < .001). The addition of CAC score to clinical risk factors increased the C-statistic from 0.677 to 0.739 (P < .001) and tAUC at 10 years from 0.668 to 0.771, respectively. In subgroup analyses, the incremental prognostic value of CAC score was more significant in participants with low/borderline- (<7.5%) and intermediate- (7.5%-20%) 10-year ASCVD risk scores.

Conclusions

The inclusion of CAC score in global risk assessment was found to significantly improve the classification of incident ASCVD events in participants with suspected nonalcoholic hepatic steatosis, indicating a potential role for CAC screening in risk assessment.

This study compared the prognostic value of quantified thoracic artery calcium (TAC) including aortic arch on chest CT and coronary artery calcium (CAC) score on ECG-gated cardiac CT.

Methods

A total of 2412 participants who underwent both chest CT and ECG-gated cardiac CT at the same period were included in the Multi-Ethnic Study of Atherosclerosis Exam 5. All participants were monitored for incident atherosclerotic cardiovascular disease (ASCVD) events. TAC is defined as calcification in the ascending aorta, aortic arch and descending aorta on chest CT. The quantification of TAC was measured using the Agatston method. Time-dependent receiver-operating characteristic (ROC) curves were used to compare the prognostic value of TAC and CAC scores.

Results

Participants were 69±9 years of age and 47% were male. The Spearman correlation between TAC and CAC scores was 0.46 (p<0.001). During the median follow-up period of 8.8 years, 234 participants (9.7%) experienced ASCVD events. In multivariable Cox regression analysis, TAC score was independently associated with increased risk of ASCVD events (HR 1.31, 95% CI 1.09 to 1.58) as well as CAC score (HR 1.82, 95% CI 1.53 to 2.17). However, the area under the time-dependent ROC curve for CAC score was greater than that for TAC score in all participants (0.698 and 0.641, p=0.031). This was particularly pronounced in participants with borderline/intermediate and high 10-year ASCVD risk scores.

Conclusion

Our study demonstrated a significant association between TAC and CAC scores but a superior prognostic value of CAC score for ASCVD events. These findings suggest TAC on chest CT provides supplementary data to estimate ASCVD risk but does not replace CAC on ECG-gated cardiac CT.