Serum calcium: a new, independent, prospective risk factor for myocardial infarction in middle-aged men followed for 18 years

Cross-sectional association between blood cholesterol and calcium levels in genetically diverse strains of mice

Genetically diverse outbred mice allow for the study of genetic variation in the context of high dietary and environmental control. Using a machine learning approach, we investigated clinical and morphometric factors that associate with serum cholesterol levels in 840 genetically unique Diversity Outbred mice of both sexes (n = 417 male and 423 female), and on both a control chow (% kcals in diet: protein 22%, carbohydrate 62%, fat 16%, no cholesterol) and high fat high sucrose (% kcals in diet: protein 15%, carbohydrate 41%, fat 45%, 0.05% cholesterol). We find expected elevations of cholesterol in male mice, as well as in mice with elevated serum triglycerides and/or fed a high fat high sucrose diet. The third strongest predictor was serum calcium which correlated with serum cholesterol across both diets and sexes (r = 0.39-0.48) in both Diversity Outbred (P = 3.0 × 10-43 ) and BXD (P = 0.005) mice. This is in-line with several human cohort studies which show associations between calcium and cholesterol, and calcium as an independent predictor of cardiovascular events.

Cross-sectional association between blood cholesterol and calcium levels in genetically diverse strains of mice

Genetically diverse outbred mice allow for the study of genetic variation in the context of high dietary and environmental control. Using a machine learning approach we investigated clinical and morphometric factors that associate with serum cholesterol levels in 840 genetically unique mice of both sexes, and on both a control chow and high fat high sucrose diet. We find expected elevations of cholesterol in male mice, those with elevated serum triglycerides and/or fed a high fat high sucrose diet. The third strongest predictor was serum calcium which correlated with serum cholesterol across both diets and sexes (r=0.39-0.48). This is in-line with several human cohort studies which show associations between calcium and cholesterol, and calcium as an independent predictor of cardiovascular events.

Calciprotein Particles Cause Physiologically Significant Pro-Inflammatory Response in Endothelial Cells and Systemic Circulation

Calciprotein particles (CPPs) represent an inherent mineral buffering system responsible for the scavenging of excessive Ca²⁺ and PO₄^3- ions in order to prevent extraskeletal calcification, although contributing to the development of endothelial dysfunction during the circulation in the bloodstream. Here, we performed label-free proteomic profiling to identify the functional consequences of CPP internalisation by endothelial cells (ECs) and found molecular signatures of significant disturbances in mitochondrial and lysosomal physiology, including oxidative stress, vacuolar acidification, accelerated proteolysis, Ca²⁺ cytosolic elevation, and mitochondrial outer membrane permeabilisation. Incubation of intact ECs with conditioned medium from CPP-treated ECs caused their pro-inflammatory activation manifested by vascular cell adhesion molecule 1 (VCAM1) and intercellular adhesion molecule 1 (ICAM1) upregulation and elevated release of interleukin (IL)-6, IL-8, and monocyte chemoattractant protein-1/ C-C motif ligand 2 (MCP-1/CCL2). Among the blood cells, monocytes were exclusively responsible for CPP internalisation. As compared to the co-incubation of donor blood with CPPs in the flow culture system, intravenous administration of CPPs to Wistar rats caused a considerably higher production of chemokines, indicating the major role of monocytes in CPP-triggered inflammation. Upregulation of sICAM-1 and IL-8 also suggested a notable contribution of endothelial dysfunction to systemic inflammatory response after CPP injections. Collectively, our results demonstrate the pathophysiological significance of CPPs and highlight the need for the development of anti-CPP therapies.

Association between serum calcium level and in-hospital mortality in patients with acute myocardial infarction: a retrospective cohort study

The association between serum calcium levels and the prognosis of patients with acute myocardial infarction (AMI) remains controversial. This study aimed to explore the association between serum calcium and in-hospital mortality in patients with AMI. The data of this study were extracted from the Philips eICU Collaborative Research Database. A total of 7284 patients were eventually enrolled in this study, of which 799 (10.97%) died during hospitalization. For each patient, serum calcium, corrected to albumin, was calculated and categorized into four groups: Q1 ≤ 8.5, Q2 8.5-9.5, Q3 9.5-10.5, and Q4 > 10.5 mg/dL. Multivariate analysis demonstrated that corrected sCa was an independent predictor of in-hospital death (Q2 vs. Q1, OR 0.5, 95% CI 0.4-0.7, P < 0.001; Q3 vs. Q1, OR 0.8, 95% CI 0.6-1.0, P = 0.035; Q4 vs. Q1, OR 1.6, 95% CI 1.1-2.3, P = 0.008). The association remained stable in the fully adjusted model. A significant U-shaped association between corrected serum calcium and in-hospital mortality was observed in piecewise linear regression model (Corrected sCa < 9.4 mg/dL, OR 0.8, 95% CI 0.7-0.9, P < 0.001; corrected sCa > 9.4 mg/dL, OR 1.5, 95% CI 1.3-1.8, P < 0.001). In conclusion, both decreased and increased corrected serum calcium is associated with increased in-hospital mortality in patients with AMI, and patients may have the lowest risk of in-hospital death when corrected serum calcium is 9.4 mg/dL (2.35 mmol/L).

The synergy between diurnal temperature range and calcium concentration help to predict hospital mortality in patients with acute myocardial infarction

Epidemiological studies have suggested that cold is an important contributor to acute cardiovascular events and mortality. However, little is known about the Diurnal Temperature Range (DTR) impact on mortality of the patients with myocardial infarction. Calcium ions (Ca²⁺) play a vital role in the human body, such as cardiac electrophysiology and contraction. To investigate whether DTR on admission moderates the association between serum calcium and in-hospital mortality in patients with acute myocardial infarction (AMI). This retrospective study enrolled consecutive adult patients with AMI at a single center in China (2003–2012). Patients were divided into four groups (Ca-Q1–4) according to serum calcium concentration quartiles. Multivariate logistic regression modeling was used to assess whether DTR moderated the association between serum calcium and in-hospital mortality. The predictive value of serum calcium was evaluated by receiver operating characteristic (ROC) curve and net reclassification improvement (NRI) analyses. The study included 3780 patients. In-hospital mortality was 4.97% (188/3780). DTR moderated the association between serum calcium and in-hospital mortality (P-interaction = 0.020). Patients with low serum calcium in the highest DTR quartile exhibited an increased risk of in-hospital mortality (odds ratio for Ca-Q4 vs. Ca-Q1, 0.03; 95% confidence interval [95% CI], 0.01–0.20). In the highest DTR quartile, adding serum calcium concentration to the risk factor model increased the area under the ROC curve (0.81 vs. 0.76; P < 0.001) and increased NRI by 20.2% (95% CI 7.5–32.9; P = 0.001). Low serum calcium was an independent risk factor for in-hospital mortality in patients with AMI, and this association was moderated by DTR. Careful attention should be paid to patients with low serum calcium who experience a higher DTR on admission.

Temporal relationship between serum calcium and triglyceride-glucose index and its impact on the incident of the acute coronary syndrome: a cross-lagged panel study

BACKGROUND

Serum calcium (Ca) and insulin resistance (IR) can have impact on each other and both are associated with the acute coronary syndrome (ACS). The triglyceride-glucose (TyG) index is a surrogate marker of IR that can be easily calculated from fasting glucose and fasting triglyceride.

AIM

We aimed to investigate the temporal relationship between serum Ca and the TyG index and its impact on ACS development.

METHODS

We retrospectively collected 2856 eligible patients in this longitudinal observational study. Patients' basal characteristics and laboratory values, including serum Ca and TyG index, were noted at baseline and after a median 4-year (3-6 years) follow-up period at two different times. Cross-lagged panel analysis was performed to demonstrate the temporal relationship between serum Ca and the TyG index. The incidence of ACS was noted, and mediation analysis was used to detect the mediation effect of variables on the ACS.

RESULTS

Baseline serum Ca and TyG index were associated with follow-up serum Ca and TyG index. The path coefficient from baseline serum Ca to the follow-up TyG index was significantly different from the baseline TyG index to the follow-up serum Ca, which indicated a reciprocal temporal relationship. The TyG index had a mediation effect of 23.5% on the serum Ca-ACS association in the total population.

CONCLUSION

There was a reciprocal temporal relationship between serum Ca and the TyG index, and both were associated with the risk of incident ACS. The TyG index mediation effect on the association of serum Ca with ACS was 23.5%.

The association of dental pulp stones to cardiovascular and renal diseases: A systematic review and meta-analysis

BACKGROUND

Pulp stone (PS) is a dystrophic calcification in the tooth's pulp chamber and was suggested in the literature to be associated with other calcifications in the body. This study aimed to investigate the association of PS to cardiovascular diseases (CVD) and renal stones (RS).

METHODS

Three databases were searched until June 2021 in addition to manual searching of Google Scholar and grey literature. Original studies were only included and critically appraised using an adapted version of the Newcastle-Ottawa scale. The odds ratio (OR) effect measure was calculated using the Mantel-Haenszel statistical test (95% confidence interval [CI]) to investigate the association of PS with CVD and or RS (p-value ˂ 0.05).

RESULTS

The database search identified 4933 studies, and 19 studies were finally included. The risk of bias was low in thirteen studies, moderate in four studies, and high in two studies. The meta-analysis of the moderate-and-low risk of bias studies revealed a significant association between PS and CVD (OR 3.35, 95% CI 1.91-5.89, P < 0.001, I² = 65%), but no association was found between PS and RS. The results also revealed an association between PS and CVD in patients older than 40 (OR 8.78, 95% CI 3.64-21.17, P < 0.001, I² = 0%).

CONCLUSIONS

The current study results showed an association between PS and CVD, but no association was found between PS and RS. PS in patients younger than 40 years, compared to older patients (> 40 years), was associated with CVD.

Calciprotein Particles Link Disturbed Mineral Homeostasis with Cardiovascular Disease by Causing Endothelial Dysfunction and Vascular Inflammation

An association between high serum calcium/phosphate and cardiovascular events or death is well-established. However, a mechanistic explanation of this correlation is lacking. Here, we examined the role of calciprotein particles (CPPs), nanoscale bodies forming in the human blood upon its supersaturation with calcium and phosphate, in cardiovascular disease. The serum of patients with coronary artery disease or cerebrovascular disease displayed an increased propensity to form CPPs in combination with elevated ionised calcium as well as reduced albumin levels, altogether indicative of reduced Ca²⁺-binding capacity. Intravenous administration of CPPs to normolipidemic and normotensive Wistar rats provoked intimal hyperplasia and adventitial/perivascular inflammation in both balloon-injured and intact aortas in the absence of other cardiovascular risk factors. Upon the addition to primary human arterial endothelial cells, CPPs induced lysosome-dependent cell death, promoted the release of pro-inflammatory cytokines, stimulated leukocyte adhesion, and triggered endothelial-to-mesenchymal transition. We concluded that CPPs, which are formed in the blood as a result of altered mineral homeostasis, cause endothelial dysfunction and vascular inflammation, thereby contributing to the development of cardiovascular disease.

Vitamin D, Calcium Supplements, and Implications for Cardiovascular Health: JACC Focus Seminar

Vitamin D and calcium supplements are commonly used, often together, to optimize bone health. Multiple observational studies have linked low serum 25-hydroxyvitamin D concentrations with increased cardiovascular risk. However, subsequent randomized controlled trials (RCTs) failed to demonstrate cardiovascular benefit with vitamin D supplementation. Although vitamin D supplements do not appear to be harmful for cardiovascular health, the lack of benefit in RCTs should discourage their use for this purpose, favoring optimizing vitamin D status through healthy lifestyles such as specific foods and modest sunlight exposure. Furthermore, some (but not all) observational and RCT studies of calcium supplementation have suggested potential for cardiovascular harm. Therefore, calcium supplementation should be used cautiously, striving for recommended intake of calcium predominantly from food sources. In this review, the authors examine the currently available evidence investigating whether vitamin D and calcium supplements are helpful, harmful, or neutral for cardiovascular health.

Plasma Ionized Calcium and Risk of Cardiovascular Disease: 106 774 Individuals from the Copenhagen General Population Study

BACKGROUND

Circulating total calcium or albumin-adjusted calcium is a risk factor for cardiovascular disease. As the biologically active ionized calcium is a physiologically more relevant measure and its association with cardiovascular disease is poorly understood, we tested the hypothesis that high plasma ionized calcium is associated with higher risk of myocardial infarction and ischemic stroke in individuals in the general population.

METHODS

We included 106 774 individuals from the Copenhagen General Population Study, and defined hypocalcemia and hypercalcemia by the lowest and highest 2.5 percentiles, respectively, using the central 95% reference interval. Information on myocardial infarction and ischemic stroke was from registries and risks calculated using Cox regression and Fine and Gray competing-risks regression.

RESULTS

During a median follow-up of 9.2 years, 4932 individuals received a diagnosis of either myocardial infarction or ischemic stroke. Hypercalcemia was associated with subdistribution hazard ratios of 1.67 (95%CI: 1.05-2.67) for myocardial infarction, 1.28 (0.81-2.02) for ischemic stroke, and of 1.54 (1.10-2.15) for the combined endpoint compared to individuals with plasma ionized calcium within the reference interval; hypocalcemia was not associated with cardiovascular disease. In models using plasma ionized calcium as a continuous variable, the associations were nonlinear; above the median, each 0.1 mmol/L higher plasma ionized calcium was associated with a hazard ratio of 1.31(1.02-1.68) for myocardial infarction, 1.21 (0.95-1.54) for ischemic stroke, and of 1.28 (1.08-1.53) for the combined endpoint.

CONCLUSIONS

High plasma ionized calcium is associated with higher risk of myocardial infarction and ischemic stroke compared to plasma ionized calcium within the reference interval.

Admission Serum Ionized and Total Calcium as New Predictors of Mortality in Patients with Cardiogenic Shock

Background

Although serum calcium has been proven to be a predictor of mortality in a wide range of diseases, its prognostic value in critically ill patients with cardiogenic shock (CS) remains unknown. This retrospective observational study is aimed at investigating the association of admission calcium with mortality among CS patients.

Methods

Critically ill patients diagnosed with CS in the Medical Information Mart for Intensive Care-III (MIMIC-III) database were included in our study. The study endpoints included 30-day, 90-day, and 365-day all-cause mortalities. First, admission serum ionized calcium (iCa) and total calcium (tCa) levels were analyzed as continuous variables using restricted cubic spline Cox regression models to evaluate the possible nonlinear relationship between serum calcium and mortality. Second, patients with CS were assigned to four groups according to the quartiles (Q1-Q4) of serum iCa and tCa levels, respectively. In addition, multivariable Cox regression analyses were used to assess the independent association of the quartiles of iCa and tCa with clinical outcomes.

Results

A total of 921 patients hospitalized with CS were enrolled in this study. A nonlinear relationship between serum calcium levels and 30-day mortality was observed (all P values for nonlinear trend < 0.001). Furthermore, multivariable Cox analysis showed that compared with the reference quartile (Q3: 1.11 ≤ iCa < 1.17 mmol/L), the lowest serum iCa level quartile (Q1: iCa < 1.04 mmol/L) was independently associated with an increased risk of 30-day mortality (Q1 vs. Q3: HR 1.35, 95% CI 1.00-1.83, P = 0.049), 90-day mortality (Q1 vs. Q3: HR 1.36, 95% CI 1.03-1.80, P = 0.030), and 365-day mortality (Q1 vs. Q3: HR 1.28, 95% CI 1.01-1.67, P = 0.046) in patients with CS.

Conclusions

Lower serum iCa levels on admission were potential predictors of an increased risk of mortality in critically ill patients with CS.

Parathyroid gland disorders and cardiovascular disease

The review provides systematic information on the relation between pathology of parathyroid glands and cardiovascular disease (CVD). Recent studies have shown that actions of parathyroid hormone (PTH) and calcium affect the heart and vasculature through downstream actions of their receptors in the myocardium and endothelial cells, which lead to higher incidence of CVD among patients with parathyroid gland disorders (PGD). The mechanisms underlying this association also include insulin resistance and altered renin-angiotensinaldosterone axis among patients with primary hyperparathyroidism. However, low calcium and PTH level in hypoparathyroid patients are characterized by higher values of arterial stiffness, electrocardiogram abnormalities, vascular atherosclerosis and remodeling. These factors contribute to low quality of life among those patients. Knowledge of cardiovascular disease pathogenesis in patients with hyper- or hypoparathyroidism could help to improve quality of diagnostic and treatment and decrease the burden of cardiac risk factors. This review will be of interest to endocrinologists and cardiologists, and other specialists.

Cardiovascular safety of calcium, magnesium and strontium: what does the evidence say?

Calcium, magnesium and strontium have all been implicated in both musculoskeletal and cardiovascular health and disease. However, despite these three elements being closely chemically related, there is marked heterogeneity of their characteristics in relation to cardiovascular outcomes. In this narrative review, we describe the relevant evidential landscape, focusing on clinical trials where possible and incorporating findings from observational and causal analyses, to discern the relative roles of these elements in musculoskeletal and cardiovascular health. We conclude that calcium supplementation (for bone health) is most appropriately used in combination with vitamin D supplementation and targeted to those who are deficient in these nutrients, or in combination with antiosteoporosis medications. Whilst calcium supplementation is associated with gastrointestinal side effects and a small increased risk of renal stones, purported links with cardiovascular outcomes remain unconvincing. In normal physiology, no mechanism for an association has been elucidated and other considerations such as dose response and temporal relationships do not support a causal relationship. There is little evidence to support routine magnesium supplementation for musculoskeletal outcomes; greater dietary intake and serum concentrations appear protective against cardiovascular events. Strontium ranelate, which is now available again as a generic medication, has clear anti-fracture efficacy but is associated with an increased risk of thromboembolic disease. Whilst a signal for increased risk of myocardial infarction has been detected in some studies, this is not supported by wider analyses. Strontium ranelate, under its current licence, thus provides a useful therapeutic option for severe osteoporosis in those who do not have cardiovascular risk factors.

Prevalence and risk factors for coronary artery disease in patients on chronic hemodialysis

Introduction: Cardiovascular diseases (CVD) represent the leading cause of morbidity and mortality (46 - 60%) among patients with chronic kidney disease (CKD). Three methods are used for kidney function replacement in patients with end-stage renal disease: hemodialysis, pertioneal dialysis and kidney transplantation. About 40% of the dialysis population develop coronary artery disease (CAD) due to chronic metabolic and inflammatory disorders. Risk factors for developing CAD in this group of patients include chronic anemia, secondary hyperparathyroidism, chronic inflammation, insulin resistance and volume overload. Aim: To determine the impact of metabolic and inflammatory disorders in developing CAD in patients with CKD that are chronically treated with hemodialysis. Material and methods: This case-control study included 115 patients with end-stage renal disease that were treated in Hemodialysis ward, Clinic for Nephrology, University Clinical Centre of Serbia. Data were collected for the period from January 2015 to December 2020. Elective coronarography was used to determine the presence and the characteristics of CAD. We also analyzed patient's laboratory findings, their demographic and clinical characteristics, as well as primary renal disease that led to the development of CKD in these patients. Additional parameters used in this study included the presence of Diabetes mellitus (DM) and duration of hemodialysis. Results: Coronary artery disease was diagnosed in 19 out of 115 patients (16.5%). Patients with CAD had a significantly higher levels of serum calcium (2.3 to 2.2 mmol/L) (p = 0.039), while other laboratory parameters did not show significant correlation. Most of the patients with CAD were male (16 of 19 patients, 84.3%, p = 0.01), while 31.6% (6 of 19 patients) with CAD were diagnosed with Diabetes mellitus (p = 0.009). Conclusion: The presence of Diabetes mellitus, higher calcium level, as well as male gender signicifantly increase the risk of developing CAD in patients chronically treated with hemodialysis.

Serum electrolyte/metabolite abnormalities among patients with acute myocardial infarction: comparison between patients with and without diabetes mellitus

Background: Diabetes mellitus (DM) in a setting of acute myocardial infarction (AMI) is associated with significant metabolic changes and worse outcomes.Objective: To evaluate the prevalence and the prognostic significance of electrolyte/metabolite disturbances among AMI patients with vs. without DM.Methods: Patients admitted to a tertiary medical center with AMI throughout 2002-2012 were screened. Exclusion criteria were: dialysis, mechanical ventilation, and in-hospital coronary artery bypass graft (CABG) surgery. All the results of the following analyses were obtained: Glucose, Uric Acid, (UA) Calcium, Magnesium, Albumin, Potassium, and Sodium. The primary outcome was in-hospital all-cause mortality.Results: A total of 14,364 AMI patient admissions was evaluated, mean age 68.1 ± 14.4 years, 65.5% males, and 41.2% with DM. Following an adjustment to potential confounders, DM patients had increased risk for significant hyperglycemia, hyperuricemia, hypercalcemia, hypomagnesemia, hyperkalemia, and hyponatremia as well as significantly decreased risk for hypoglycemia, hypermagnesemia, and hypokalemia compared with nondiabetics. Overall, 681 (4.7%) patients died throughout the index admission. Deceased had an increased incidence of electrolyte/metabolite abnormalities versus hospital survivors. The prognostic significance of the different categories of the investigated variables is very similar among diabetics and nondiabetics, except increased and decreased uric acid levels [<4.5 (men); <4.0 (women) and ≥9.0 (men); ≥9.4 (women)] which are associated with worse outcomes among diabetics while hyperglycemia (Glucose ≥213 mg/dL) and increased Potassium levels (Potassium ≥4.4mEq/L) which comprise significantly worse prognosis among nondiabetics.Conclusions: Patients with DM admitted with AMI are at greater risk for electrolyte/metabolite abnormalities which are associated with increased risk for in-hospital mortality. The latter association is similar among patients with and without DM except for hyperglycemia and increased potassium levels (stronger among nondiabetics).

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.

Point-of-care platelet function tests: relevance to arterial thrombosis and opportunities for improvement

Studies using whole blood platelet aggregometry as a laboratory research tool, provided important insights into the mechanism and modulators of platelet aggregation. Subsequently, a number of point-of-care (POC) platelet function tests (PFTs) were developed for clinical use, based on the concept that an individual’s thrombotic profile could be assessed in vitro by assessing the response to stimulation of platelet aggregation by specific, usually solo agonists such as adenosine diphosphate (ADP), collagen and thrombin. However, adjusting antiplatelet medication in order to improve the results of such POC PFTs has not translated into a meaningful reduction in cardiovascular events, which may be attributable to important differences between the POC PFT techniques and in vivo conditions, including patient-to-patient variability. Important limitations of most tests include the use of citrate-anticoagulated blood. Citrate directly and irreversibly diminishes platelet function and even after recalcification, it may result in altered platelet aggregation in response to ADP, epinephrine or collagen, and interfere with thrombin generation from activated platelets. Furthermore, most tests do not employ flowing blood and therefore do not assess the effect of high shear forces on platelets that initiate, propagate and stabilize arterial thrombi. Finally, the effect of endogenous thrombolysis, due to fibrinolysis and dislodgement, which ultimately determines the outcome of a thrombotic stimulus, is mostly not assessed. In order to accurately reflect an individual’s predisposition to arterial thrombosis, future tests of thrombotic status which overcome these limitations should be used, to improve cardiovascular risk prediction and to guide pharmacotherapy.

Association of serum calcium and phosphorus with measures of left ventricular structure and function: The ARIC study

BACKGROUND AND AIMS

Elevated serum calcium and phosphorus have been associated with increased risk of cardiovascular disorders. We evaluated whether abnormal calcium and high serum phosphorus are associated cross-sectionally with echocardiographic measures of left ventricular (LV) structure and function, as doing so may provide insight into the etiology of cardiac disorders.

METHODS AND RESULTS

Included in the analysis were 5213 Atherosclerosis Risk in Communities Study (ARIC) participants who in 2011-2013 had echocardiography and serum calcium and phosphorus measurements. We evaluated the association of serum calcium (corrected for albumin) and phosphorus quintiles with measures of LV structure and function, after adjusting for other cardiovascular risk factors. Participants were on average 75.3 years old; 59.1% were female and 19.8% were African American. Mean (±SD) concentrations of calcium and phosphorus were 9.33 ± 0.38 and 3.46 ± 0.45 mg/dL, respectively. Higher calcium was associated with lower LV end-diastolic diameter (LVEDD) but greater prevalence of concentric remodeling (p-trend: 0.005 and 0.004 respectively). We observed association between high phosphorus and high septal E/e' (p-trend: 0.02). Likewise, higher serum phosphorus was associated with higher left atrial volume index (p-trend: 0.001) and LV hypertrophy prevalence (p-trend: 0.04).

CONCLUSIONS

In conclusion, higher calcium was associated with more concentric remodeling but lower LVEDD, suggesting complex associations between calcium and cardiac function. Serum phosphorus was related to worse indices of LV diastolic function and LV hypertrophy, but not to LV systolic function. However, the magnitudes of association were modest, so clinical implications of these findings may be limited.

Cardiovascular consequences of parathyroid disorders in adults

PTH is a metabolic active hormone primarily regulating calcium and phosphate homeostasis in a very tight and short term-manner. Parathyroid disorders in adult patients reflect a variety of different conditions related either to the parathyroid glands itself or to the effects of the secreted hormone. The clinical spectrum varies from the common disease primary hyperparathyroidism (PHPT) to the orphan conditions pseudohypoparathyroidism (Ps-HypoPT) and chronic hypoparathyroidism (HypoPT). The purpose of this review is to describe the consequences of disturbances in levels or action of PTH for cardiac function and cardiovascular risk in adult patients with these disorders. Most patients with PHPT achieve the diagnose by chance and have minor or no specific symptoms. Still, these patients with mild PHPT do possess cardiovascular (CV) morbidity, however so far not proven ameliorated by surgery in controlled trials. In severe cases, the CV risk is increased and with a potential reversibility by treatment. Patients with Ps-HypoPT have resistance to PTH action, but not necessarily total resistance in all tissues. So far, no clear CV morbidity or risk has been demonstrated, but there are several aspects of interest for further studies. Most patients with HypoPT do get their hormonal deficiency syndrome following neck surgery. These patients do experience multiple symptoms and do have an increased CV-risk before the primary surgery. Based on existing data, their CV mortality do not deviate from the expected when adjusting for the preexisting increased risk. Patients with nonsurgical (NS-) HypoPT do demonstrate increased CV-risk also associated with exposure time. Endocrine disorders with alterations in PTH function have major impact on the cardiovascular system of importance for morbidity and mortality, wherefore management of these specific diseases should be optimized currently, as new data become available, however also avoiding over-treating asymptomatic patients.

Usefulness of Serum Calcium in the Risk Stratification of Midterm Mortality among Patients with Acute Coronary Syndrome

Serum calcium has been reported to be a predictor of short-term prognosis; however, evidence regarding its association with midterm mortality is scarce. We investigated the association between serum calcium levels at admission and midterm mortality in a retrospective cohort of 2594 consecutive patients with acute coronary syndrome (ACS) who presented to the First Affiliated Hospital of Harbin Medical University from November 2014 to December 2016. Patients were assigned to 4 groups according to the quartiles of serum calcium levels (Ca-Q1-4) and were followed longitudinally for the time to all-cause death. During a median follow-up period of 21.8 months (17.5∼29.5, IQR), 124 patients died (4.8%) of all causes. Kaplan-Meier curves showed that the incidence of midterm mortality differed significantly (log-rank P=0.038) among the quartiles of serum calcium levels at admission. After adjustment for the confounders that were significant in the univariate analysis, the hazard ratios for the lowest quartile of serum calcium was 1.86 (95% CI, 1.05-3.31; P=0.033), compared with the third quartile (reference group). A multiple restricted cubic spline regression model suggested a reverse J-shaped association between serum calcium levels and midterm mortality, and the lowest risk of mortality was associated with approximately 2.32 mmol/l of serum calcium. In conclusion, the serum calcium level is an independent predictor of all-cause midterm mortality among ACS patients. Patients with abnormal serum calcium levels at admission need more targeted treatments.

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.

Increasing extracellular Ca2+ sensitizes TNF-alpha-induced vascular cell adhesion molecule-1 (VCAM-1) via a TRPC1/ERK1/2/NFκB-dependent pathway in human vascular endothelial cells

Increasing circulating Ca²⁺ levels within the normal range has been reported to positively correlate with the incidence of fatal cardiovascular diseases (CVDs). However, limited studies have been able to delineate the potential mechanism(s) linking circulating Ca²⁺ to CVD. In this study, we exposed primary human umbilical vein endothelial cells (HUVECs) and human umbilical vein cell line (EA.hy926) to different extracellular Ca²⁺ to mimic the physiological state. Our data revealed that increasing extracellular Ca²⁺ significantly enhanced susceptibility to tumor necrosis factor (TNF)-alpha-stimulated vascular cell adhesion molecule (VCAM)-1 expression and monocytes adhesion. Knocking-down VCAM-1 by siRNA abolished calcium-induced monocytes adhesion on HUVECs. Follow up mechanistic investigations identified that extracellular Ca²⁺-increased calcium influx contributed to the activation of VCAM-1. This was mediated via upregulation of transient receptor potential channel (TRPC)1 in a nuclear factor (NF)κB-dependent manner. Most importantly, we found that a novel TRPC1-regulated extracellular signal-regulated kinase 1/2 (ERK1/2) pathway exclusively contributed to calcium-induced NFκB activation. This study provided direct evidence that increasing extracellular Ca²⁺ enhanced TNF-alpha-induced VCAM-1 activation and monocytes adhesion. Moreover, we identified a novel TRPC1/ERK1/2/NFκB signaling pathway mediating VCAM-1 activation and monocyte adhesion in this pathological process. Our studies indicate that blood calcium levels should be strictly monitored to help prevent CVD, and that TRPC1 might act as a potential target for the treatment and prevention against increased circulating calcium-enhanced CVDs.

Risk of Ischemic Stroke Associated With Calcium Supplements With or Without Vitamin D: A Nested Case-Control Study

BACKGROUND

There is controversy surrounding the risk of ischemic stroke associated with the use of calcium supplements either in monotherapy or in combination with vitamin D.

METHODS AND RESULTS

A nested case-control study was performed with patients aged 40 to 89 years old, among whom a total of 2690 patients had a first episode of nonfatal ischemic stroke and for which 19 538 controls were randomly selected from the source population and frequency-matched with cases for age, sex, and calendar year. Logistic regression provided the odds ratios while adjusting for confounding factors. A sensitivity analysis was performed by restricting to patients who were new users of calcium supplements as either monotherapy or with vitamin D. Calcium supplementation with vitamin D was not associated with an increased risk of ischemic stroke (odds ratio 0.85; 95% confidence interval, 0.67-1.08) in the population as a whole or under any of the conditions examined (dose, duration, background cardiovascular risk, sex, or age). Calcium supplement monotherapy was not associated with an increased risk in the population as a whole (odds ratio 1.18; 95% confidence interval, 0.86-1.61), although a significant increased risk at high doses (≥1000 mg/day: odds ratio 2.09; 95% confidence interval, 1.25-3.49; <1000 mg: odds ratio 0.76; 95% confidence interval, 0.45-1.26) compared with nonuse was observed. The sensitivity analysis did not affect the inferences, with similar results observed among new users as to the overall study population.

CONCLUSIONS

This study suggests that calcium supplements given as monotherapy at high doses may increase the risk of ischemic stroke, whereas their combination with vitamin D seems to offset this hazard.

Associations between serum levels of calcium, parathyroid hormone and future risk of venous thromboembolism: the Tromsø study

OBJECTIVE

The relationship between serum levels of calcium, parathyroid hormone (PTH) and risk of venous thromboembolism (VTE) has not been addressed in population-based cohorts. We investigated the associations between serum levels of calcium and PTH, with future risk of VTE in a general adult population.

DESIGN

Population-based cohort.

METHODS

A total of 27 712 subjects (25-87 years) who participated in Tromsø 4 (1994-1995) and Tromsø 5 (2001-2002) surveys were included in the study, and total calcium and PTH were measured in 27 685 and 8547 subjects respectively. Incident VTE was recorded through December 31, 2012. Cox-regression models with calcium and PTH as time-varying exposures were used to calculate hazard ratios (HR) of VTE by quartiles of calcium and PTH. Quartiles of calcium and PTH were also combined to assess the effect of discordants of both PTH and calcium (e.g. highest and lowest quartiles of both calcium and PTH) on VTE risk using the middle two quartiles as reference.

RESULTS

There were 712 VTEs during 15.0 years of median follow-up. Serum levels of calcium and PTH were not associated with risk of VTE. However, subjects with discordant high serum levels of both calcium and PTH (calcium ≥2.45 mmol/L and PTH ≥4.0 pmol/L) had increased risk of VTE compared to those in subjects with normal calcium and PTH (multivariable HR: 1.78, 95% CI: 1.12-2.84).

CONCLUSIONS

Serum levels of calcium and PTH separately were not associated with future risk of VTE, but subjects with high levels of both calcium and PTH had increased risk of VTE compared to those in subjects with normal levels.

The role of calcium supplementation in healthy musculoskeletal ageing : An expert consensus meeting of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) and the International Foundation for Osteoporosis (IOF)

The place of calcium supplementation, with or without concomitant vitamin D supplementation, has been much debated in terms of both efficacy and safety. There have been numerous trials and meta-analyses of supplementation for fracture reduction, and associations with risk of myocardial infarction have been suggested in recent years. In this report, the product of an expert consensus meeting of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) and the International Foundation for Osteoporosis (IOF), we review the evidence for the value of calcium supplementation, with or without vitamin D supplementation, for healthy musculoskeletal ageing. We conclude that (1) calcium and vitamin D supplementation leads to a modest reduction in fracture risk, although population-level intervention has not been shown to be an effective public health strategy; (2) supplementation with calcium alone for fracture reduction is not supported by the literature; (3) side effects of calcium supplementation include renal stones and gastrointestinal symptoms; (4) vitamin D supplementation, rather than calcium supplementation, may reduce falls risk; and (5) assertions of increased cardiovascular risk consequent to calcium supplementation are not convincingly supported by current evidence. In conclusion, we recommend, on the basis of the current evidence, that calcium supplementation, with concomitant vitamin D supplementation, is supported for patients at high risk of calcium and vitamin D insufficiency, and in those who are receiving treatment for osteoporosis.

Oxidative stress and angiogenesis in primary hyperparathyroidism

Background

The inappropriate elevation of parathormone (PTH), which regulates the process of angiogenesis in parathyroid tissue, causes the changes of activity of enzymes responsible for the removal of free radicals. Parathyroidectomy (PTX) in patients with primary hyperparathyroidism (PHPT) lowers the level of PTH and leads to the reduction of risk of cardiovascular and all-cause mortality by normalization of the antioxidant status. Therefore, the aims of the study were to assess the activity of antioxidant enzymes and free radical reaction products in patients after parathyroidectomy, and to evaluate the correlation between the systemic oxidative stress and angiogenic parameters.

Materials and methods

Patients with PHPT treated surgically were enrolled into the study. Total antioxidant capacity (TAC), total oxidative status (TOS), oxidative stress index (OSI), superoxide dismutase (SOD), ceruloplasmin (CER), lipid hydroperoxides (LHP) and malondialdehyde (MDA) were measured before and after parathyroidectomy. The immunohistological expression of angiogenic factors in parathyroid specimens was assessed by the BrightVision method from ImmunoLogic using murine monoclonal anti-human: anti-VEGF, anti-CD31 and anti-CD106 antibodies.

Results

The significant increase of TAC, CER, reduction of TOS, MDA, SOD, especially for cytoplasmic form, and significant decrease of OSI, LHP were observed after PTX. There was no significant correlation between changes of oxidative stress markers and angiogenic parameters: VEGF, CD-31, CD-106 in parathyroid tissue. The correlation level was low and medium.

Conclusions

Parathyroidectomy causes down-regulation of lipid peroxidation processes and leads to reduction of oxidative stress in patients with PHPT. The decrease in the OSI is the results of down-regulation of oxidative stress in the postoperative period. The change of the antioxidant status has no impact on angiogenesis processes in parathyroid tissue.

Low Relative Lean Mass is Associated with Increased Likelihood of Abdominal Aortic Calcification in Community-Dwelling Older Australians

Age-related loss of skeletal muscle is associated with increased risk of functional limitation and cardiovascular (CV) mortality. In the elderly abdominal aortic calcification (AAC) can increase CV risk by altering aortic properties which may raise blood pressure and increase cardiac workload. This study investigated the association between low muscle mass and AAC in community-dwelling older Australians. Data for this cross-sectional analysis were drawn from a 2010 sub-study of the Melbourne Collaborative Cohort Study in the setting of community-dwelling older adults. Three hundred and twenty-seven participants [mean age = 71 ± 6 years; mean BMI = 28 ± 5 kg/m(2); females n = 199 (62 %)] had body composition determined by dual-energy x-ray absorptiometry (DXA) and AAC determined by radiography. Participants were stratified into tertiles of sex-specific BMI-normalised appendicular lean mass (ALM). Those in the lowest tertile were considered to have low relative muscle mass. Aortic calcification score (ACS) was determined visually as the extent of calcification on the aortic walls between L1 and L4 vertebrae (range: 0-24). Severe AAC was defined as ACS ≥ 6. Prevalence of any AAC was highest in participants with low relative muscle mass (74 %) compared to the middle (65 %) and upper (53 %) tertiles (p trend = 0.006). The lower ALM/BMI tertile had increased odds (Odds ratio = 2.3; 95 % confidence interval: 1.1-4.6; p = 0.021) of having any AAC; and having more severe AAC (2.2; 1.2-4.0; p = 0.009) independent of CV risk factors, serum calcium and physical activity. AAC is more prevalent and severe in community-dwelling older adults with low relative muscle mass. Maintaining muscle mass could form part of a broader primary prevention strategy in reducing AAC.

Association between serum calcium concentration and risk of incident and fatal cardiovascular disease in the prospective AMORIS study

BACKGROUND AND AIMS

Previous epidemiological studies have shown positive associations between serum calcium concentration and risk of cardiovascular disease (CVD), but results differ by definition of CVD. We examined the association of circulating calcium with incident and fatal CVD, myocardial infarction (MI), and stroke in the Swedish AMORIS cohort.

METHODS

We included 441,738 participants of the AMORIS database linked for follow-up information on morbidity and mortality. Concentrations of total calcium were fully automated measured using a colorimetric method; concentrations of albumin were measured with a bromocresol green method between 1985 and 1995. The association of albumin-corrected calcium concentration and risk of incident and fatal CVD, MI, and stroke, respectively, was assessed with multivariable adjusted Cox proportional hazards models.

RESULTS

Until December 31, 2011, during a median follow-up time of 21 years, 90,866 incident cases of CVD, 21,271 of MI, and 25,810 of stroke were identified. High serum calcium concentrations were associated with increased risk of non-fatal CVD (Hazard ratio [HR] = 1.12, 95% CI 1.10-1.14, top [≥2.40 nmol/L] vs. bottom [≤2-25 nmol/L] quintile), MI (1.19, 1.14-1.25), and stroke (1.11, 1.06-1.15) and fatal disease (CVD: 1.41, 1.35-1.47; MI: 1.41, 1.31-1.51; stroke: 1.30, 1.20-1.41). Effect modification by sex was observed for incident disease such that associations were stronger among women than men. Serum calcium was positively associated with both incident and fatal ischemic stroke and with fatal hemorrhagic stroke, but not with incident hemorrhagic stroke. In a sub-groups analysis, the results remained significant after adjustment for smoking.

CONCLUSIONS

The results support a modest positive association between serum calcium and risk of CVD, but the underlying mineral metabolism and the exact mechanisms are currently unclear.

Apoptosis-mediated endothelial toxicity but not direct calcification or functional changes in anti-calcification proteins defines pathogenic effects of calcium phosphate bions

Calcium phosphate bions (CPB) are biomimetic mineralo-organic nanoparticles which represent a physiological mechanism regulating the function, transport and disposal of calcium and phosphorus in the human body. We hypothesised that CPB may be pathogenic entities and even a cause of cardiovascular calcification. Here we revealed that CPB isolated from calcified atherosclerotic plaques and artificially synthesised CPB are morphologically and chemically indistinguishable entities. Their formation is accelerated along with the increase in calcium salts-phosphates/serum concentration ratio. Experiments in vitro and in vivo showed that pathogenic effects of CPB are defined by apoptosis-mediated endothelial toxicity but not by direct tissue calcification or functional changes in anti-calcification proteins. Since the factors underlying the formation of CPB and their pathogenic mechanism closely resemble those responsible for atherosclerosis development, further research in this direction may help us to uncover triggers of this disease.

Association of serum calcium concentrations with fibrinogen and homocysteine in nondiabetic Korean subjects

Considerable evidence shows that increased serum calcium levels are associated with metabolic disorders, cardiovascular disease, and increased mortality. This study investigated whether serum calcium, within a normal range, is significantly associated with serum fibrinogen and homocysteine, markers of increased cardiovascular disease risk in nondiabetic Korean subjects.A cross-sectional analysis was performed on 1096 subjects (mean age, 55.1 ± 11.1 years; 36.1% women) undergoing a general health checkup. Serum biochemistry was analyzed including serum albumin-corrected calcium (Cac), insulin resistance (IR, using homeostasis model assessment [HOMA]), fibrinogen, and homocysteine.Compared with patients within the lowest Cac quartile, those with higher Cac levels had increased fibrinogen and homocysteine levels as well as an increased proportion of smoking, dyslipidemia, and HOMA-IR. Correlation analyses revealed linear relationships for Cac with fibrinogen and homocysteine in both genders. After adjustment for confounding factors, serum Cac was significantly associated with high fibrinogen (odds ratio [OR] for the highest vs the lowest quartile = 1.76, 95% confidence interval [CI] = 1.09-2.83, P = 0.02) and homocysteine (OR = 1.83, 95% CI = 1.07-3.11, P = 0.027). Multivariate regression models showed that Cac was linearly associated with fibrinogen (standardized β = 0.14, P < 0.001) and homocysteine (standardized β = 0.07, P = 0.009).High normal calcium concentrations were independently associated with increased levels of fibrinogen and homocysteine. Further investigation is needed to validate whether slightly increased calcium levels within the normal range indicate a higher risk of cardiovascular disease.

Circulating calcium concentrations, vascular disease and mortality: a systematic review

Associations between serum calcium and vascular disease have been reported, but the consistency of these findings is unknown. We conducted a systematic review to determine whether circulating calcium concentrations are associated with risks of cardiovascular disease and death in normocalcaemic populations. We conducted PubMed searches up to 18 December 2014 and scrutinized reference lists of papers. Eligible studies related serum calcium to mortality or cardiovascular events in humans. A follow-up of at least one year was required for longitudinal studies. Studies in populations selected on the basis of renal disease or abnormal serum calcium were excluded. Two investigators performed independent data extraction. The results were tabulated and, where possible, meta-analysed. Five of 11 studies reported a statistically significant positive association between serum calcium and mortality. Meta-analysis of eight of these studies showed a hazard ratio of death of 1.13 (1.09, 1.18) per standard deviation of serum calcium. Eight of 13 studies reported a statistically significant positive association between serum calcium and cardiovascular disease. Meta-analysis of eight studies showed a hazard ratio of cardiovascular disease of 1.08 (1.04, 1.13) per standard deviation of serum calcium. For two studies reporting odds ratios, the pooled odds ratio per standard deviation was 1.22 (1.11, 1.32). When hazard ratios adjusted for cardiovascular risk factors were meta-analysed, the pooled hazard ratio was 1.04 (1.01, 1.08). Other studies demonstrated associations between serum calcium and stroke and between serum calcium and direct measurements of arterial disease and calcification. These observational data indicate that serum calcium is associated with vascular disease and death, but they cannot determine causality.

Cardiovascular complications of calcium supplements

There is longstanding concern that calcium supplements might increase cardiovascular risk in patients with renal impairment. The Auckland Calcium Study suggested that the same problem occurs in older people taking these supplements for prevention of osteoporosis. Our subsequent meta-analyses, (which followed protocols finalized before the data was available) confirmed that calcium supplements, with or without vitamin D, adversely affected risk of myocardial infarction and, possibly, stroke. Several groups have re-visited these data, consistently finding an adverse effect of calcium on myocardial infarction, not always statistically significant because some meta-analyses have been under-powered. Whether or not an adverse effect of calcium plus vitamin D on myocardial infarction is found depends on whether two specific groups of subjects are included-those in the Women's Health Initiative who were already taking calcium at the time of randomization, and subjects from an open, cluster-randomized study in which baseline cardiovascular risk was different between groups. Vitamin D alone does not affect vascular risk, so it is unlikely that differences between calcium alone and calcium plus vitamin D are real, and they are more likely to result from the inclusion of studies at high risk of bias. The mechanisms of the adverse cardiovascular effects are uncertain but may be mediated by the increase in serum calcium following supplement ingestion, and the effects of this on vascular function and coagulation. Available evidence suggests the risks of calcium supplements outweigh any small benefits on fracture incidence, so the case for their use is weak.

Low serum calcium is associated with left ventricular systolic dysfunction in a Chinese population with coronary artery disease

Whether serum calcium is associated with heart systolic function in patients with established coronary artery disease (CAD) and acute myocardial infarction (AMI) remains to be elucidated. This study is aimed to assess the association between serum calcium and left ventricular systolic dysfunction in a Chinese population of CAD. The cross-sectional study included 5938 CAD patients with and without AMI in China. The factors associated with AMI and left ventricular ejection fraction (LVEF) were evaluated. The data showed that AMI patients had lower serum calcium levels (2.11 ± 0.13 vs 2.20 ± 0.10 mmol/l, P < 0.001) than those without AMI. Multiple logistic regression analysis exhibited that serum calcium (OR: 0.000, 95% CI: 0.000–0.001) was one of the independent factors correlated with AMI. CAD patients with and without AMI when LVEF <50% had lower serum calcium levels than those when LVEF ≥50% respectively. Serum calcium was independently associated with LVEF and LVEF <50% in CAD patients with and without AMI respectively using multivariate analysis. The independent association between serum calcium and LVEF still existed among CAD patients when LVEF ≥50%. Serum calcium levels are significantly decreased following AMI. Low serum calcium is independently correlated with left ventricular systolic dysfunction in CAD patients with and without AMI.

Mortality associated with primary hyperparathyroidism

561 patients with primary hyperparathyroidism were followed between 1961 and 1994. Relative survival was compared to that of the Australian population studied during the same time interval. Mortality was significantly greater in the hyperparathyroid population (P<0.001). Mortality was not greater in the patients with serum calcium levels >3.00 mmol/L compared to those with a serum calcium levels <3.00 mmol/L. 113 patients did not have parathyroid surgery. Their relative survival was not significantly different from those who had surgery but their mean serum calcium and parathyroid hormone (PTH) levels were significantly lower than those who had surgery. A re-analysis of the 453 patients followed between 1972 and 2011 was carried out and a 20-year survival analysis made of those diagnosed between 1972 and 1981 and those diagnosed between 1982 and 1991. The latter group had significantly worse relative mortality than the former group (P<0.001) but was significantly older at the time of diagnosis (56.94 ± 14.83 vs 52.01 ± 13.58, P<0.001). The serum calcium and serum PTH levels were not significantly different between these two groups.

Cross-sectional analysis of serum calcium levels for associations with left ventricular hypertrophy in normocalcemia individuals with type 2 diabetes

Background

Left ventricular hypertrophy (LVH) is prevalent in patients with type 2 diabetes mellitus (T2DM). Recent studies show that an increase in albumin-adjusted serum calcium level is associated with an elevated risk of T2DM. We speculate that increased serum calcium levels in T2DM patients are related to LVH prevalence.

Methods

In this echocardiographic study, 833 normocalcemia and normophosphatemia patients with T2DM were enrolled. The associations between serum calcium and metabolic parameters, left ventricular mass index (LVMI), as well as the rate of LVH were examined using bivariate linear correlation, multivariate linear regression and logistic regression, respectively. The predictive performance of serum calcium for LVH was evaluated using the area under the receiver operating characteristic curve (AUC).

Results

Patients with LVH have significantly higher serum calcium than those without LVH. Serum calcium was positively associated with total cholesterol, triglycerides, low-density lipoprotein cholesterol, serum uric acid, HOMA-IR and fasting plasma glucose. Multivariate linear regression analysis demonstrated that serum calcium was independently associated with LVMI (p < 0.001). In comparison with patients in the lowest serum calcium quartile, the odds ratio (OR) for LVH in patients in the highest quartile was 2.909 (95% CI 1.792-4.720; p < 0.001). When serum calcium was analyzed as a continuous variable, per 1 mg/dl increase, the OR (95% CI) for LVH was [2.400 (1.552-3.713); p < 0.001]. Serum calcium can predict LVH (AUC = 0.617; 95% CI (0.577-0.656); p < 0.001).

Conclusions

Albumin-adjusted serum calcium is associated with an increased risk of LVH in patients with T2DM.

The renin-angiotensin-aldosterone system and calcium-regulatory hormones

There is increasing evidence of a clinically relevant interplay between the renin-angiotensin-aldosterone system and calcium-regulatory systems. Classically, the former is considered a key regulator of sodium and volume homeostasis, while the latter is most often associated with skeletal health. However, emerging evidence suggests an overlap in regulatory control. Hyperaldosteronism and hyperparathyroidism represent pathophysiologic conditions that may contribute to or perpetuate each other; aldosterone regulates parathyroid hormone and associates with adverse skeletal complications, and parathyroid hormone regulates aldosterone and associates with adverse cardiovascular complications. As dysregulation in both systems is linked to poor cardiovascular and skeletal health, it is increasingly important to fully characterize how they interact to more precisely understand their impact on human health and potential therapies to modulate these interactions. This review describes the known clinical interactions between these two systems including observational and interventional studies. Specifically, we review studies describing the inhibition of renin activity by calcium and vitamin D, and a potentially bidirectional and stimulatory relationship between aldosterone and parathyroid hormone. Deciphering these relationships might clarify variability in outcomes research, inform the design of future intervention studies and provide insight into the results of prior and ongoing intervention studies. However, before these opportunities can be addressed, more effort must be placed on shifting observational data to the proof of concept phase. This will require reallocation of resources to conduct interventional studies and secure the necessary talent.

Evaluation of left ventricle functions by tissue Doppler, strain, and strain rate echocardiography in patients with primary hyperparathyroidism

Cardiovascular morbidity and mortality are increased in patients with primary hyperparathyroidism (PHPT). We aimed to evaluate left ventricle systolic and diastolic functions with tissue Doppler imaging (TDI) and strain and strain rate echocardiography in patients with PHPT. Thirty-one patients with PHPT and 29 healthy controls were evaluated with conventional and pulse Doppler echocardiography, TDI and strain and strain rate echocardiography. Myocardial performance index (MPI) was calculated. Strain and peak systolic strain rate in mid and basal segments of lateral, anterior, inferior, and septal walls of left ventricle were determined. TDI showed similar late diastolic myocardial peak velocity in two groups. Peak systolic mitral annular velocity, early diastolic myocardial peak velocity, and ratio of early to late diastolic myocardial peak velocity were lower in PHPT patients (p = 0.01, p < 0.001 and p < 0.001, respectively). MPI calculated by TDI was 0.53 ± 0.15 in PHPT group and 0.44 ± 0.09 in control group (p = 0.013). Strain values were lower in mid and basal segments of septum, lateral and anterior walls, and basal segment of inferior wall in PHPT patients. Mean systolic strain was -20.88 ± 2.30 and -24.25 ± 2.13 in PHPT patients and control group, respectively (p < 0.001). Mean strain rate was lower in PHPT patients compared to control group (-1.38 ± 0.19 vs -1.57 ± 0.25) (p = 0.002). Patients with PHPT, but no cardiac symptoms or documented cardiovascular disease, have subclinical systolic and diastolic myocardial dysfunction. Evaluation of these patients with TDI and S and Sr echocardiography in addition to conventional echocardiography might be valuable to detect subclinical cardiac involvement.

Serum magnesium, phosphorus, and calcium are associated with risk of incident heart failure: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Heart failure (HF) is a major source of morbidity and mortality, particularly among the elderly. Magnesium, phosphorus, and calcium are micronutrients traditionally viewed in relation to bone health or chronic kidney disease. However, they also may be associated with risk of cardiovascular disease through a broad range of physiologic roles.

OBJECTIVE

With the use of data from the Atherosclerosis Risk in Communities (ARIC) cohort, we tested the hypotheses that the incidence of HF is greater among individuals with low serum magnesium and those with high serum phosphorus and calcium.

DESIGN

A total of 14,709 African Americans (27%) and whites from the ARIC cohort [aged 45-64 y at baseline (1987-1989)] were observed through 2009. Proportional hazards regression was used to explore associations between biomarkers and incident HF. Serum calcium was corrected for serum albumin. Models were adjusted for demographics, behaviors, and physiologic characteristics.

RESULTS

A total of 2250 incident HF events accrued over a median follow-up of 20.6 y. Participants in the lowest (≤1.4 mEq/L) compared with the highest (≥1.8 mEq/L) category of magnesium were at greater HF risk (HR: 1.71; 95% CI: 1.46, 1.99). For phosphorus, there appeared to be a threshold whereby only those in the highest quintile were at greater HF risk [HR(Q5 vs Q1): 1.34; 95% CI: 1.16, 1.54]. Higher concentrations of calcium were also associated with greater risk of HF [HR(Q5 vs Q1): 1.24; 95% CI: 1.07, 1.43]. Results were not modified by race, sex, or kidney function and were similar when incident coronary heart disease was included as a time-varying covariate.

CONCLUSIONS

Low serum magnesium and high serum phosphorus and calcium were independently associated with greater risk of incident HF in this population-based cohort. Whether these biomarkers will be useful candidates for HF risk prediction or targets for prevention remains to be seen.

Calcium and phosphate concentrations and future development of type 2 diabetes: the Insulin Resistance Atherosclerosis Study

AIMS/HYPOTHESIS

Low phosphate and high calcium concentrations have been linked to altered glucose tolerance and reduced insulin sensitivity in non-diabetic individuals. The aim of this study was to examine the relationships of calcium and phosphate levels and the calcium-phosphate product with the development of type 2 diabetes.

METHODS

Participants were 863 African-Americans, Hispanics and non-Hispanic whites in the Insulin Resistance Atherosclerosis Study who were free of diabetes at baseline. The mean follow-up period was 5.2 years. The insulin sensitivity index (SI) and acute insulin response (AIR) were directly measured using the frequently sampled IVGTT.

RESULTS

Calcium concentration (OR per 1 SD unit increase, 1.26 [95% CI 1.04, 1.53]) and calcium-phosphate product (OR 1.29 [95% CI 1.04, 1.59]) were associated with incident diabetes after adjustment for demographic variables, family history of diabetes, and 2 h glucose. The relationship between phosphate concentration and progression to diabetes was close to statistical significance (OR 1.21 [95% CI 0.98, 1.49]). Calcium concentration (OR 1.37 [95% CI 1.09, 1.72]) and calcium-phosphate product (OR 1.39 [95% CI 1.09, 1.77]) remained associated with incident diabetes after additional adjustment for BMI, plasma glucose, SI, AIR, C-reactive protein, estimated GFR, diuretic drugs and total calcium intake.

CONCLUSIONS/INTERPRETATION

Elevated serum calcium and calcium-phosphate product are associated with increased risk of developing type 2 diabetes independently of measured glucose, insulin secretion and insulin resistance. Future studies need to analyse the role of calcium-phosphate homeostasis in the pathophysiology of diabetes.

Association of admission serum calcium levels and in-hospital mortality in patients with acute ST-elevated myocardial infarction: an eight-year, single-center study in China

OBJECTIVE

The relationship between admission serum calcium levels and in-hospital mortality in patients with acute ST-segment elevation myocardial infarction (STEMI) has not been well definitively explored. The objective was to assess the predictive value of serum calcium levels on in-hospital mortality in STEMI patients.

METHODS

From 2003 to 2010, 1431 consecutive STEMI patients admitted to the First Affiliated Hospital of Nanjing Medical University were enrolled in the present study. Patients were stratified according to quartiles of serum calcium from the blood samples collected in the emergency room after admission. Between the aforementioned groups,the baseline characteristics, in-hospital management, and in-hospital mortality were analyzed. The association of serum calcium level with in-hospital mortality was calculated by a multivariable Cox regression analysis.

RESULTS

Among 1431 included patients, 79% were male and the median age was 65 years (range, 55-74). Patients in the lower quartiles of serum calcium, as compared to the upper quartiles of serum calcium, were older, had more cardiovascular risk factors, lower rate of emergency revascularization,and higher in-hospital mortality. According to univariate Cox proportional analysis, patients with lower serum calcium level (hazard ratio 0.267, 95% confidence interval 0.164-0.433, p<0.001) was associated with higher in-hospital mortality. The result of multivariable Cox proportional hazard regression analyses showed that the Killip's class≥3 (HR = 2.192, p = 0.026), aspartate aminotransferase (HR = 1.001, p<0.001), neutrophil count (HR = 1.123, p<0.001), serum calcium level (HR = 0.255, p = 0.001), and emergency revascularization (HR = 0.122, p<0.001) were significantly and independently associated with in-hospital mortality in STEMI patients.

CONCLUSIONS

Serum calcium was an independent predictor for in-hospital mortality in patients with STEMI. This widely available serum biochemical index may be incorporated into the current established risk stratification model of STEMI patients. Further studies are required to determine the actual mechanism and whether patients with hypocalcaemia could benefit from calcium supplement.

Interactions between adrenal-regulatory and calcium-regulatory hormones in human health

PURPOSE OF REVIEW

To summarize the evidence characterizing the interactions between adrenal-regulating and calcium-regulating hormones, and the relevance of these interactions to human cardiovascular and skeletal health.

RECENT FINDINGS

Human studies support the regulation of parathyroid hormone (PTH) by the renin-angiotensin-aldosterone system (RAAS): angiotensin II may stimulate PTH secretion via an acute and direct mechanism, whereas aldosterone may exert a chronic stimulation of PTH secretion. Studies in primary aldosteronism, congestive heart failure, and chronic kidney disease have identified associations between hyperaldosteronism, hyperparathyroidism, and bone loss, which appear to improve when inhibiting the RAAS. Conversely, elevated PTH and insufficient vitamin D status have been associated with adverse cardiovascular outcomes, which may be mediated by the RAAS. Studies of primary hyperparathyroidism implicate PTH-mediated stimulation of the RAAS, and recent evidence shows that the vitamin D-vitamin D receptor complex may negatively regulate renin expression and RAAS activity. Ongoing human interventional studies are evaluating the influence of RAAS inhibition on PTH and the influence of vitamin D receptor agonists on RAAS activity.

SUMMARY

Although previously considered independent endocrine systems, emerging evidence supports a complex web of interactions between adrenal-regulating and calcium-regulating hormones, with implications for human cardiovascular and skeletal health.

Elevated brain lesion volumes in older adults who use calcium supplements: a cross-sectional clinical observational study

Recent studies have implicated Ca supplements in vascular risk elevation, and therefore these supplements may also be associated with the occurrence of brain lesions (or hyperintensities) in older adults. These lesions represent damage to brain tissue that is caused by ischaemia. In the present cross-sectional clinical observational study, the association between Ca-containing dietary supplement use and lesion volumes was investigated in a sample of 227 older adults (60 years and above). Food and supplemental Ca intakes were assessed with the Block 1998 FFQ; participants with supplemental Ca intake above zero were categorised as supplement users. Lesion volumes were determined from cranial MRI (1.5 tesla) scans using a semi-automated technique; volumes were log-transformed because they were non-normal. ANCOVA models revealed that supplement users had greater lesion volumes than non-users, even after controlling for food Ca intake, age, sex, race, years of education, energy intake, depression and hypertension (Ca supplement use: β = 0.34, SE 0.10, F(1,217)= 10.98, P= 0.0011). The influence of supplemental Ca use on lesion volume was of a magnitude similar to that of the influence of hypertension, a well-established risk factor for lesions. Among the supplement users, the amount of supplemental Ca was not associated with lesion volume (β = - 0.000035, SE 0.00 015, F(1,139)= 0.06, P= 0.81). The present study demonstrates that the use of Ca-containing dietary supplements, even low-dose supplements, by older adults may be associated with greater lesion volumes. Evaluation of randomised controlled trials is warranted to determine whether this relationship is a causal one.

The role of calcium in the prevention of cardiovascular disease--a review of observational studies and randomized clinical trials

Calcium is a mineral that is important for bone health and has also been suggested to play a role in the prevention of cardiovascular disease (CVD). Lately, the potential effects of both inadequate and excessive calcium intake have received growing attention. In this review, we summarize the evidence from experimental, epidemiologic, and clinical studies investigating the role of calcium intake, either from the diet or from supplements, as well as blood concentrations, in relation to the risk of CVD in adults. In vitro and in vivo laboratory studies suggest that calcium may be involved in CVD development through multiple pathways, including blood cholesterol, insulin secretion and sensitivity, vasodilation, inflammatory profile, thrombosis, obesity, and vascular calcification. Several prospective epidemiologic studies have examined how dietary or supplemental calcium intake is associated with CVD incidence or mortality in middle-aged and older adults, and the results are inconsistent. Prospective studies investigating blood concentrations of calcium have also reported mixed results. However, changes in blood calcium concentrations may reflect a disturbed calcium phosphate balance, which is associated with increased risk of CVD. To date there is no randomized clinical trial that has been designed specifically to test the effect of calcium supplementation on the risk of CVD as the primary end point. Existing trials have performed secondary analyses, and most of them have been conducted among postmenopausal women. These trials suggest that calcium supplementation has no effect on CVD development; however, they do not allow a definitive conclusion to be drawn. The average daily intake of calcium is low in many populations; however, the evidence for a potential role of dietary or supplemental calcium in the prevention of CVD remains insufficient and inconclusive. Only large-scale randomized trials designed to investigate the effects of calcium supplementation on CVD events as the primary end point, as well as short-term trials investigating the effect on coronary biomarkers, can provide a definitive answer.