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Warranty Period of a Calcium Score of Zero
Quick Takes
- Based on the MESA study, the ACC/AHA guidelines have concluded that with a CAC = 0, it is reasonable to withhold or delay statins and re-scan in 5-10 years.
- This study refines the re-scan time period providing a range of 3-7 years with a useful illustration demonstrating longer times in diabetes and Chinese persons, but not in smokers or those with family history of CHD.
- Considering the very low cost and safety of statins, and that this analysis in the MESA study was not adequately powered to assess the value of statin in intermediate- and high-risk persons, diabetes, family history of premature CHD, and hypertension in middle-aged persons, a CAC = 0 should not be used to avoid statins.
Study Questions:
Is there an appropriate time interval for repeating noncontrast computed tomography (CT) coronary artery calcium score (CAC) studies in persons with a baseline CAC = 0, which infers there is a warranty period with rare coronary heart disease (CHD) events?
Methods:
The study included 3,116 participants from the MESA study (Multi-Ethnic Study of Atherosclerosis) with baseline CAC = 0 and follow-up scans over 10 years. All with CAC = 0 underwent ≥1 follow-up scan, all had one repeat within 4 years, and about 50% had a second repeat scan between 4-10 years. Prevalence of incident CAC, defined by thresholds of CAC >0, CAC >10, or CAC >100, was calculated and time to progression was derived from a parametric survival model. Warranty periods were modeled as a function of sex, race/ethnicity, cardiovascular risk and risk factors, and desired yield of repeated CAC testing. Further analysis was performed of the proportion of coronary events occurring in participants with baseline CAC = 0 that preceded and followed repeated CAC testing at different time intervals. Total CHD endpoints included hard CHD events (CHD death, resuscitated arrest, and myocardial infarction), and definite or probable angina with revascularization.
Results:
Mean follow-up was 12.6 years, mean age 58 years with 40% ≥60 years, 63% women, White and Black each >30%, Hispanic 23%, and Chinese 12%. Mean 10-year atherosclerotic cardiovascular disease (ASCVD) estimate was 14% with 31% low (<5%), 44% intermediate (>5-20%), and 25% high risk (>20%). Prevalence of CAC >0, CAC >10, and CAC >100 was 52%, 36%, and 8%, respectively, at 10 years. Using a 25% testing yield (number needed to re-scan [NNS] = 4), the estimated warranty period of CAC >0 varied from 3-7 years depending on sex and race/ethnicity (longest in Chinese persons). About 11% increased to CAC >0 by year 2, 20% in years 0-4, 25% 0-6, and 50% by 10 years. Approximately 15% of participants progressed to CAC >10 in 5-8 years, whereas 10-year progression to CAC >100 was rare. Presence of diabetes was associated with a significantly shorter warranty period, whereas family history and smoking had small effects. A total of 19% of all 10-year coronary events occurred in CAC = 0 prior to performance of a subsequent scan at 3-5 years, whereas detection of new CAC >0 preceded 55% of future events and identified individuals at threefold higher risk of coronary events.
Conclusions:
In persons with baseline CAC = 0, the data from MESA provide reasonable time to re-scan to detect progression to CAC >0, CAC >10, and CAC >100 that correlate with detectable and missed 10-year CHD events. Beyond age, sex, and race/ethnicity, diabetes also has a significant impact on the warranty period. The study suggests that evidence-based guidance would be to consider re-scanning in 3-7 years depending on individual demographics and risk profile.
Perspective:
Over a 15-year follow-up, there is a high correlation between CAC score and future ASCVD events, cancer, and total mortality. This study provides good evidence for choosing an interval for re-scanning when a CAC = 0 is used to avoid treatments. But that does not infer the indication for CAC is to reduce the number of persons treated with statins, aspirin, or blood pressure management in persons with or without diabetes or family history of premature ASCVD. Guidelines based on estimating risk for CHD and stroke do not assess longevity or quality of life after potentially preventable events.
Clinical Topics: Cardiac Surgery, Cardiovascular Care Team, Dyslipidemia, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Cardiac Surgery and Arrhythmias, Cardiac Surgery and SIHD, Nonstatins, Novel Agents, Statins, Interventions and Imaging, Computed Tomography, Nuclear Imaging, Smoking
Keywords: Angina Pectoris, Aspirin, Atherosclerosis, Blood Pressure, Coronary Disease, Diabetes Mellitus, Diagnostic Imaging, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Myocardial Infarction, Myocardial Revascularization, Plaque, Atherosclerotic, Primary Prevention, Risk Factors, Smoking, Stroke, Tomography, X-Ray Computed
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