Hypocalcemia predicts 12-month re-hospitalization in heart failure.

Background Potential pathophysiology of heart failure with preserved ejection fraction (HFpEF) has not been fully explored. The aim of the study was to reveal the association of serum calcium concentration at baseline with 12-month clinical outcome in the disease. Materials and methods A total of 350 patients with newly diagnosed HFpEF were included in this prospective observational study. There were no malignant tumour, kidney disease, thyroid disease, calcium and vitamin D supplements in the patients. All of them received 12-month follow-up, and endpoints were cardiac re-hospitalization and death. Baseline serum calcium concentration was measured using AIA2000ST enzyme immunoassay analyser. Cardiopulmonary exercise, six-minute walk distance test, EQ5D questionnaire and cardiac ultrasound were performed to evaluate exercise capacity, quality of life and left ventricle function. Results Multivariate COX regression analysis revealed that baseline hypocalcaemia was associated with the increased risk of cardiac re-hospitalization and death during the follow-up period (HR: 2.10, 95% CI: 1.69-2.61; HR: 8.26, 95% CI: 2.88-23.70). Furthermore, baseline hypocalcaemia was related to the deterioration of 6-minute walk distance, quality of life score (EQ-5D), right quadriceps strength, left atrium volume index and left ventricular ejection fraction during the follow-up period (HR: 1.65, 95% CI: 1.21-2.26; HR: 1.55, 95% CI: 1.12-2.11; HR: 2.56, 95% CI: 1.68-3.89; HR: 1.44, 95% CI: 1.03-1.98; HR: 1.36, 95% CI: 1.02-1.80). Conclusion Baseline hypocalcaemia predicted 12-month cardiac re-hospitalization and death in HFpEF patients without calcium and vitamin D supplements partly through left ventricle and skeletal muscle function pathways.