Association between Serum Calcium and First Incident Acute Myocardial Infarction: A Cross-Sectional Study

Background: The role of serum calcium in coronary artery disease (CAD) patients with or without first incident acute myocardial infarction has not been studied previously. This study aimed to assess the relationship between serum calcium and first incident acute myocardial infarction. Methods: This cross-sectional study was conducted from Jan 2014 to Dec 2016. All the participants were from our database, described in detail elsewhere including 1609 cases and 3252 controls. Multiple logistic regression was carried out to explore the effect of serum calcium on first incident acute myocardial infarction. Interaction between serum calcium and risk factors were evaluated. Results: Patients with first incident acute myocardial infarction have significantly lower serum calcium concentrations than those without acute myocardial infarction (2.18 (0.21) vs 2.24 (0.19) mmol/L, P<0.0001). After adjusting for sex and age, logistic regression showed that serum calcium was significantly associated with first incident acute myocardial infarction (odds ratio (OR): 1.50, 95% confidence interval (CI): 1.41-1.60). Further adjusted for potential confounders, serum calcium was associated with first incident acute myocardial infarction (OR: 1.32, 95% CI: 1.22-1.42). Moreover, the association still existed when patients were divided into subgroups according to gender and age. A significant interaction was found between serum calcium and diabetes mellitus (DM), lipoprotein (a) (Lp (a)), and serum albumin. Conclusion: Serum calcium was associated with first incident acute myocardial infarction among CAD patients in both sexes and in age categories. This study provides further evidence showing the value of serum calcium levels in clinical practice.