Can Coronary Calcium Scores Decrease?
Coronary artery calcium scores do not decrease with medical therapy; in fact, statin therapy typically causes calcium scores to increase over time, reflecting a paradoxical "procalcific effect" on coronary atheromas despite reducing cardiovascular risk. 1
Natural Progression of Coronary Calcium
Coronary calcium progresses at approximately 10-20% of baseline value per year in untreated patients, with the natural course being one of continuous accumulation as atherosclerotic plaques mature and calcify. 1
In patients with initial CAC = 0, approximately 7% per year develop detectable coronary calcium, with conversion from CACS = 0 to CACS > 0 occurring at an average of 4.1 ± 0.9 years. 1
CAC progression >15% per year is associated with >3-fold increase in all-cause mortality, demonstrating that increasing calcium reflects worsening atherosclerotic burden and risk. 1
The Statin Paradox
Recent studies demonstrate that prolonged statin therapy has procalcific effects on coronary atheromas and can increase CAC, meaning that effective lipid-lowering therapy actually causes calcium scores to rise rather than fall. 1
This paradoxical increase likely reflects stabilization of vulnerable plaques through increased calcification, which may represent a beneficial remodeling process despite the higher numerical score. 1
Interpretation of serial CACS must account for the effects of statin therapy, as an increasing score in a treated patient does not necessarily indicate treatment failure. 1
Clinical Implications for Serial Scanning
For risk assessment, the most recent CACS result should be used rather than CAC progression, as the absolute score provides better prognostic information than rate of change. 1
There are no data demonstrating that serial CAC testing leads to improved outcomes or changes in therapeutic decision making, limiting the clinical utility of repeat scanning. 1
If follow-up scanning is considered, it should not be performed sooner than 3-5 years, as meaningful progression takes time to develop and measurement variability can confound interpretation at shorter intervals. 1, 2
When Serial Scanning May Have Limited Value
Follow-up CACS has limited value in patients with baseline CACS > 400, who are already at high risk and require aggressive medical therapy regardless of progression. 1
Repeat scanning may be most useful in patients with initial CACS = 0 who have diabetes or multiple cardiovascular risk factors, to detect conversion to positive calcium. 1
Key Clinical Pitfall
The critical error is expecting calcium scores to decrease with treatment and interpreting rising scores as treatment failure. The goal of therapy is to reduce cardiovascular events and mortality, not to lower calcium scores—which paradoxically may increase with effective statin therapy while actual cardiovascular risk decreases. 1