Importance of the Corrected Calcium Level in Patients With Acute Heart Failure Requiring Intensive Care

Background: Serum calcium (Ca) concentrations in the acute phase of acute heart failure (AHF) have not been not sufficiently investigated. Methods and Results: This study enrolled 1,291 AHF patients and divided them into 3 groups based on original and corrected Ca concentrations: (1) hypocalcemia (both original and corrected Ca ≤8.7 mg/dL; n=651); (2) pseudo-hypocalcemia (original and corrected Ca ≤8.7 and >8.7 mg/dL, respectively; n=300); and (3) normal/hypercalcemia (both original and corrected Ca >8.7 mg/dL; n=340). AHF patients were also divided into 2 groups based on corrected Ca concentrations: (1) corrected hypocalcemia (corrected Ca ≤8.7 mg/dL; n=651); and (2) corrected normal/hypercalcemia (corrected Ca >8.7 mg/dL; n=640). Of the 951 patients with original hypocalcemia (≤8.7 mg/dL), 300 (31.5%) were classified as corrected normal/hypercalcemia after correction of Ca concentrations by serum albumin. The prognoses in the pseudo-hypocalcemia, low albumin, and corrected normal/hypercalcemia groups, including all-cause death within 730 days, were significantly poorer than in the other groups. Multivariate Cox regression analysis showed that classification into the pseudo-hypocalcemia, hypoalbumin, and corrected normal/hypercalcemia groups independently predicted 730-day all-cause death (hazard ratios [95% confidence intervals] of 1.497 [1.153–1.943], 2.392 [1.664–3.437], and 1.294 [1.009–1.659], respectively). Conclusions: Corrected normal/hypercalcemia was an independent predictor of prognosis because this group included patients with pseudo-hypocalcemia, which was affected by the serum albumin concentration.