Association of Hypocalcemia With Mortality in Hospitalized Patients With Heart Failure and Chronic Kidney Disease

•In patients with heart failure (HF) and chronic kidney disease (CKD), elevated parathyroid hormone and phosphate levels have been associated with increased cardiovascular disease and mortality, but the relationship between serum calcium levels and outcomes is unknown.•Among 191 patients hospitalized with HF and CKD, 32 (17%) had hypocalcemia, defined as a corrected serum calcium level <8.4 mg/dL.•Multivariable Cox proportional hazards analysis showed hypocalcemia to be an independent predictor of all-cause mortality during follow-up.

BackgroundChronic kidney disease–mineral and bone disorders (CKD-MBD) are associated with vascular calcification and abnormal electrolytes that lead to cardiovascular disease and mortality. CKD-MBD is identified by imbalances in serum calcium (Ca), phosphate, and parathyroid hormone (PTH). Although the relation of phosphate and PTH with the prognosis of HF patients has been reported, the association of Ca with prognosis in patients with heart failure (HF) and CKD remains unclear.Methods and ResultsWe examined 191 patients admitted for HF and CKD (estimated glomerular filtration rate <60 mL min−1 1.73 m−2), and they were divided into 2 groups based on levels of corrected Ca: low Ca (Ca <8.4 mg/dL; n = 32) and normal-high Ca (8.4 ≤Ca; n = 159). We compared laboratory and echocardiographic findings, as well as followed cardiac and all-cause mortality. The low-Ca group had 1) higher levels of alkaline phosphatase (308.9 vs 261.0 U/L; P = .026), 2) lower levels of 1,25-dihydroxy vitamin D (26.1 vs 45.0 pg/mL; P = .011) and hydrogen carbonate (22.4 vs 24.5 mmol/L; P = .031), and 3) a tendency to have a higher PTH level (87.5 vs 58.6 pg/mL; P = .084). In contrast, left and right ventricular systolic function, estimated glomerular filtration rate, urine protein, phosphate, sodium, potassium, magnesium, and zinc did not differ between the 2 groups. In the Kaplan-Meier analysis, cardiac and all-cause mortality were significantly higher in the low-Ca group than in the normal-high–Ca group (P < .05). In the multivariable Cox proportional hazard analyses, hypocalcemia was an independent predictor of all-cause mortality in HF and CKD patients (P < .05).ConclusionsHypocalcemia was an independent predictor of all-cause mortality in HF and CKD patients.