Diagnostic accuracy and prognostic value of aortic valve calcification on routine non-gated ct thorax

Objectives

BSCI/BSTI guidelines recommend reporting aortic valve calcification (AVC) on all chest CT regardless of scan indication. Formal aortic valve calcium scoring can identify aortic stenosis but the clinical impact of routine reporting is unclear. This study assessed AVC prevalence, prognosis and the association between AVC on chest CT and aortic stenosis (AS) on echocardiography.

Methods

Retrospective, single-centre analysis of consecutive chest CTs (January-December 2015) for 200 patients per age group (<40, 40-49, 50-59, 60-69, 70-79, 80-89, ≥90). CTs were re-reviewed for presence and severity of AVC and coronary artery calcification (CAC). Corresponding echocardiography reports were reviewed for presence of AVC/sclerosis and AS. Comorbidities and clinical outcomes (myocardial infarction, stroke and all-cause mortality) were recorded for all included patients.

Results

1377 patients were included (mean age 64±20 years, 55% female) following exclusion of patients with incomplete imaging data or prior aortic valve replacement. 42% (587/1377) had a corresponding echocardiography report within 5 years of their CT (median time between tests 3.9 months, [IQR 0.3 - 14.7]). On re-review, AVC was observed in 508/1377 (37%), with no significant difference between males and females (p=0.876). Prevalence and severity increased with age (p<0.001). 67% (924/1377) of patients died (median follow-up 41 months). AVC predicted major adverse cardiovascular events (p<0.001; MACE) on univariate analysis, but this was not independent of age/CAC in multivariate analysis for all-cause mortality (HR 1.03 [1.0-1.05], p=0.04 [Figure 1]). 13% (31/242) of patients with any degree of AVC on chest CT had AS on echocardiography (mild AS 8% [19/242]; moderate AS 5% [11/242]; severe AS <1% [1/242]). Sensitivity and specificity for any degree of AVC predicting AS was 0.56 and 0.60 respectively, but specificity rose with increasing AVC severity category (Table 1). Extrapolating these findings to our cohort without an echocardiogram, 34 patients may have undiagnosed AS.

Conclusion

AVC on non-gated CT is common and specificity of AVC predicting AS increased with grade of AVC. AVC is a strong univariate predictor of all-cause mortality, but this effect is not independent of age or coronary artery calcification. Routine reporting of AVC on CT may identify more than 1 in 10 patients with unknown AS.

Conflict of Interest

None