Oral Calcium Supplements Associate With Serial Coronary Calcification: Insights From Intravascular Ultrasound

Objectives: This study sought to evaluate and assess the extent of serial coronary artery calcification in response to oral calcium supplementation.

Background: Oral calcium supplements are frequently used despite their cardiovascular safety remaining controversial. Their effects on serial coronary calcification are not well established.

Methods: In a post hoc patient-level analysis of 9 prospective randomized trials using serial coronary intravascular ultrasound, changes in serial percentage of atheroma volume (PAV) and calcium indices (CaI) were compared in matched segments of patients coronary artery disease who were receiving concomitant calcium supplements (n = 447) and in those who did not receive supplements (n = 4,700) during an 18- to 24-month trial period.

Results: Patients (mean age 58 ± 9 years; 73% were men; 43% received concomitant high-intensity statins) demonstrated overall annualized changes in PAV and CaI with a mean of -0.02 ± 1.9% (p = 0.44) and a median of 0.02 (interquartile range: 0.00 to 0.06) (p < 0.001) from baseline, respectively. Following propensity-weighted mixed modeling adjusting for treatment and a range of demographic, clinical, ultrasonic, and laboratory parameters (including but not limited to sex, race, baseline, and annualized change in PAV, baseline CaI, concomitant high-intensity statins, diabetes mellitus, renal function), there were no significant between-group differences in annualized changes in PAV (least-squares mean: 0.09; 95% confidence interval [CI]: -0.20 to 0.37 vs. 0.01; 95% CI: -0.27 to 0.29; p = 0.092) according to calcium supplement intake. Per a multivariable logistic regression model accounting for the range of covariates described, calcium supplementation independently associated with an increase in annualized CaI (odds ratio: 1.15; 95% CI: 1.05 to 1.26; p = 0.004).

Conclusions: Oral calcium supplementation may increase calcium deposition in the coronary vasculature independent of changes in atheroma volume. The impact of these changes on plaque stability and cardiovascular outcomes requires further investigation.