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Aortic Valve Calcium and Long-Term Risk of Severe Aortic Stenosis
Quick Takes
- This study set out to determine the prevalence of aortic valve calcification (AVC) on cardiac CT and its association with the long-term risk for developing severe aortic stenosis (AS).
- Only 13% of patients free of known cardiovascular disease had an aortic valve calcium score >0. There were significant associations of AVC with age, gender, and race/ethnicity, with older White men being the most likely to have an AVC >0.
- There was a strong association of AVC >0 with development of severe AS in this cohort. Conversely, AVC = 0 was associated with an extremely low incidence of severe AS.
Study Questions:
What is the prevalence of aortic valve calcification (AVC) on cardiac computed tomography (CT) and its association with the long-term risk for developing severe aortic stenosis (AS)?
Methods:
A total of 6,810 participants, free of known cardiovascular disease, underwent noncontrast cardiac CT as part of MESA (Multi-Ethnic Study of Atherosclerosis). AVC was quantified according to the Agatston method, and age-, sex-, and race/ethnicity-specific percentiles were derived. AVC was defined as absent (AVC = 0) or present (AVC >0) and categorized by severity (0, 1-99, 100-299, and ±300 Agatston units). Adjudication of AS was performed by two independent cardiologists through chart review of all encounters with International Classification of Diseases (ICD) codes related to aortic valve disease and supplemented by echocardiographic data. Severe AS was defined according to standard clinical criteria from: 1) echocardiography, 2) aortic valve replacement (AVR) (surgical AVR or transcatheter AVR [TAVR]) for documented severe AS, 3) AVR for moderate AS when part of coronary artery bypass grafting, or 4) clinical documentation of severe AS diagnosis. Two participants identified as having severe AS at baseline were excluded from the analysis. Association between AVC and development of severe AS was evaluated using multivariable Cox hazard ratios (HRs).
Results:
Approximately 87% of patients had an AVC score of 0 (55% women, average age 60.9 ± 9.9 years), while 13% of patients had AVC >0 (40% women, average age 70.5 ± 8.1 years, p < 0.01 for both gender and age). Significant differences were also found for race/ethnicity, with White patients having a higher probability of AVC compared to age- and gender-matched patients of all other races/ethnicities.
Incident adjudicated severe AS occurred in 84 patients (1.2%) over a median follow-up of 16.7 years. Higher AVC scores were found to be strongly associated with severe AS. For AVC groups 1-99, 100-299, and ≥300, adjusted HRs were 12.9 (95% confidence interval [CI], 5.6-29.7), 76.4 (95% CI, 34.3-170.2), and 380.9 (95% CI, 169-855) as compared to AVC of 0. Conversely, patients with AVC of 0 had an extremely low incidence of severe AS (0.1 per 1,000 patient-years).
Conclusions:
Only 13% of patients free of known cardiovascular disease had AVC >0. There were significant associations of AVC with age, gender, and race/ethnicity, with older White men being the most likely to have an AVC >0. Excluding two patients with baseline severe AS, there was a strong association of AVC of 0 with development of severe AS in this cohort, with an exponential increase in HR with increasing AVC category (i.e., 1-99, 100-299, and ≥300). Conversely, AVC = 0 was associated with an extremely low incidence of severe AS.
Perspective:
This is the first study to report normative age-, sex-, and race/ethnicity-specific data on AVC using the Agatston scoring system. AVC scores have been used already for patients with severe AS undergoing pre-TAVR evaluations to determine annular anatomy, valve size, and lend support to a diagnosis of severe AS when echo data is equivocal. However, this is the first study to establish an association between an individual’s AVC score and their long-term risk of developing severe AS. It is not surprising that this risk increased with higher calcium score, although the exponential increase in HR observed across AVC categories in this study was quite impressive. At the same time, the clinical implications of this finding are somewhat muted in the absence of viable decalcification strategies. Of more immediate clinical significance is the finding that patients with an AVC of 0 had almost no risk of developing severe AS in the long-term. This finding will need to be verified in additional studies, but could lead to practice change, especially if AVC could be included as a standard measurement in CT scans done to evaluate coronary calcium.
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Valvular Heart Disease, Aortic Surgery, Cardiac Surgery and Arrhythmias, Cardiac Surgery and VHD, Interventions and Imaging, Interventions and Structural Heart Disease, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging
Keywords: Aortic Valve Disease, Aortic Valve Stenosis, Atherosclerosis, Cardiac Surgical Procedures, Diagnostic Imaging, Echocardiography, Heart Valve Diseases, Plaque, Atherosclerotic, Risk, Secondary Prevention, Tomography, X-Ray Computed, Transcatheter Aortic Valve Replacement, Vascular Calcification
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