Serum calcium levels independently predict in-hospital mortality in patients with acute myocardial infarction

Background and aim: Serum calcium levels (sCa) were reported to be associated with cardiovascular risk factors, incidence of coronary artery disease and acute myocardial infarction (AMI). The current study evaluated the association between sCa and in-hospital mortality among AMI patients. Methods and results: Patients admitted in a tertiary medical center for AMI throughout 2002–2012 were analyzed. For each patient, mean sCa, corrected to albumin, was calculated and categorized to seven equally-sized groups: <8.9, 8.9–9.12, 9.12–9.3, 9.3–9.44, 9.44–9.62, 9.62–9.86, ≥9.86 mg/dL. The primary outcome was all-cause in-hospital mortality. Out of 12,121 AMI patients, 11,446 were included, mean age 67.1 ± 14 years, 68% Males. Mean number of sCa values for patient was 4.2 ± 7.3. Mean sCa was 9.4 ± 0.53 mg/dL, range 5.6–13.2 mg/dL sCa was significantly associated with cardiovascular risk-factors, in-hospital complications, more frequent 3-vessel coronary artery disease and decreased rate of revascularization, often in a U-shaped association. Overall 794 (6.9%) patients died in-hospital. Multivariate analysis showed a significant U-shaped association between sCa and in-hospital mortality with sCa below 9.12 mg/dL and above 9.86 mg/dL as independent predictors of significantly increased in-hospital mortality: OR = 2.4 (95% CI:1.7–3.3) and 1.7 (95%CI:1.2–2.4), for Ca<8.9 and Ca≥9.86 mg/dL respectively p < 0.01, as compared with middle rage sCa group (9.3–9.44 mg/dL). Conclusion: sCa is an independent predictor of in-hospital mortality in patients with AMI with a U-shaped association. Both increased and decreased sCa levels are associated with increased risk of in-hospital mortality.