Parameters of mineral metabolism predict midterm clinical outcome in end-stage heart failure patients

U-shaped association between serum calcium and in-hospital mortality in patients with congestive heart failure

AIMS

Serum calcium level is widely used for evaluating disease severity, but its impact on clinical outcomes in patients with congestive heart failure (CHF) remains poorly understood. The aim of this study is to investigate the relationship between serum calcium levels and in-hospital mortality in CHF patients.

METHODS AND RESULTS

We conducted a retrospective analysis utilizing clinical data from the Medical Information Mart for Intensive Care database, encompassing a cohort of 15 983 CHF patients. This cohort was stratified based on their serum calcium levels, with the primary objective being the determination of in-hospital mortality. To assess the impact of admission serum calcium levels on in-hospital mortality, we employed various statistical methodologies, including multivariable logistic regression models, a generalized additive model, a two-piecewise linear regression model, and subgroup analysis. Comparative analysis of the reference group (Q3) revealed increased in-hospital mortality in the first quintile (Q1, the group with the lowest blood calcium level) and the fifth quintile (Q5, the group with the highest blood calcium level), with fully adjusted odds ratios of 1.38 [95% confidence interval (CI): 1.13-1.68, P = 0.002] and 1.23 (95% CI: 1.01-1.5, P = 0.038), respectively. A U-shaped relationship was observed between serum calcium levels and in-hospital mortality, with the lowest risk occurring at a threshold of 8.35 mg/dL. The effect sizes and corresponding CIs below and above this threshold were 0.782 (95% CI: 0.667-0.915, P = 0.0023) and 1.147 (95% CI: 1.034-1.273, P = 0.0094), respectively. Stratified analyses confirmed the robustness of this correlation.

CONCLUSIONS

Our study identifies a U-shaped association between serum calcium levels and in-hospital mortality in CHF patients, with a notable inflection point at 8.35 mg/dL. Further investigation through prospective, randomized, and controlled studies is warranted to validate the findings presented in this study.

Determinants of circulating calcitriol in cardiovascular disease

Circulating calcitriol may contribute to the risk of cardiovascular disease (CVD), but its regulation in patients with CVD is poorly characterized. We therefore aimed to assess determinants of circulating calcitriol in these patients. We analyzed 2183 independent samples from a large cohort of patients scheduled for coronary angiography and 1727 independent samples from different other cohorts from patients with a wide range of CVDs, including heart transplant candidates, to quantify the association of different parameters with circulating calcitriol. We performed univariable and multivariable linear regression analyses using the mathematical function that fitted best with circulating calcitriol. In the multivariable analysis of the large single cohort, nine parameters remained significant, explaining 30.0 % (32.4 % after exclusion of 22 potential outliers) of the variation in circulating calcitriol (r=0.548). Log-transformed 25-hydroxyvitamin D [25(OH)D] and log-transformed glomerular filtration rate were the strongest predictors, explaining 17.6 % and 6.6 %, respectively, of the variation in calcitriol. In the analysis of the combined other cohorts, including heart transplant candidates, the multivariable model explained a total of 42.6 % (46.1 % after exclusion of 21 potential outliers) of the variation in calcitriol (r=0.653) with log-transformed fibroblast growth factor-23 and log-transformed 25(OH)D explaining 29.0 % and 6.2 %, respectively. Circulating 25(OH)D was positively and FGF-23 inversely associated with circulating calcitriol. Although significant, PTH was only a weak predictor of calcitriol in both analyses (<2.5 %). In patients with CVD, FGF-23 and 25(OH)D are important independent determinants of circulating calcitriol. The relative importance of these two parameters may vary according to CVD severity. Future studies should focus on the clinical importance of regulating circulating calcitriol by different parameters.

Narrative review of recent studies on the role of vitamin D in the prevention of cardiac and renal risk and additional considerations for COVID-19 vulnerability

The role of vitamin D in maintaining a healthy cardiovascular (CV) and the renal system has received increasing attention. Low vitamin D levels are associated with the incidence of hypertension, cardiac remodeling, and chronic congestive heart failure. Low vitamin D levels also influence renal disease progression and albuminuria deterioration. Moreover, recent research indicates that vitamin D deficiency can be a potential risk factor for coronavirus disease-19 (COVID-19) infection and poorer outcomes. Data are inconclusive as to whether supplementation with vitamin D agents reduces CV disease risk or COVID-19 severity. Conversely, in patients with kidney disease, vitamin D supplementation is associated with improved kidney function and albuminuria. This narrative review considers recent data on the effects of vitamin D on the CV and renal system, as well as its possible role regarding COVID-19 complications.

Higher Serum Phosphorus Is Not an Independent Risk Factor of Mortality in Heart Failure with Reduced Ejection Fraction

Higher serum phosphorus has detrimental health effects. Even high-normal rage sP is associated with worse outcomes. The relationship of serum phosphorus with prognostic markers in heart failure remains unclear. We investigated the association of serum phosphorus with heart failure prognostic factors and risk of mortality related to serum phosphorus. In 1029 stable heart failure patients, we investigated the distribution of markers of more advanced heart failure stage across quintiles of serum phosphorus and estimated the relative risk of mortality in comparison to reference. Higher serum phosphorus levels sP were associated with markers of a worse outcome. The best survival was observed in low-normal serum levels. The unadjusted hazard ratio for mortality increased toward higher phosphorus quintiles but not to lower levels of sP. The correction for age, sex, BMI, percent weight loss, inflammation, kidney function, and LVEF did not modify the risk profile substantially. The adjustment for NYHA, natriuretic peptides, serum sodium, and treatment characteristics broke down the risk relationship completely. A higher serum phosphorus is associated with markers of a more risky profile of heart failure. Elevated serum levels of phosphorus sP does not provide independent prognostic information beyond the strongest markers of the severity of the syndrome. The potential involvement of higher serum phosphorus as a mediator in the pathophysiology of heart failure warrants further study.

Parathormone, vitamin D and the risk of atrial fibrillation in older adults: A prospective study

BACKGROUND & AIMS

Vitamin D and parathormone (PTH) have been associated with cardiovascular outcomes, but their impact on atrial fibrillation (AF) onset is still unclear. We explored the influence of serum 25-hydroxyvitamin D (25[OH]D) and PTH on AF risk in older adults.

METHODS AND RESULTS

Data come from 2418 participants enrolled in the Progetto Veneto Anziani study. Serum 25(OH)D and intact PTH were measured using radioimmunoassay and two-site immunoassay, respectively. The associations between 25(OH)D, PTH and adjudicated AF cases over 4-years were explored by Cox regression. Over the follow-up, 134 incident cases of AF were assessed. The incidence rate of the sample was 13.5 (95%CI 11.4-15.9) per 1000 person-years, and was higher among those with high PTH levels (high: 16.4 [95%CI 11.3-24.0] per 1000 person-years), especially when associated to low 25(OH)D (20.3 [95%CI 12.9-32.3] per 1000 person-years). At Cox regression, only high PTH was significantly associated to an increased risk of AF (HR = 1.90, 95%CI 1.27-2.84). A marginal significant interaction (p = 0.06) was found between 25[OH]D and PTH concentrations in influencing AF risk. When exploring the risk of AF for combined categories of 25(OH)D and PTH, we found that those with high PTH and low 25(OH)D levels had an AF risk twice as high as that of people with normal values (HR = 2.09, 95%CI 1.28-3.42).

CONCLUSION

The risk of AF may be increased by high PTH levels, especially when associated with 25(OH)D deficiency. The identification and treatment of high PTH or vitamin D deficiency may thus contribute to lower the risk of AF.

The Association Between Serum Calcium Levels and Short-Term Mortality in Patients with Chronic Heart Failure

BACKGROUND

Patients with chronic heart failure have vulnerable myocardial function and are susceptible to electrolyte disturbances. In these patients, diuretic treatment is frequently prescribed, though it is known to cause electrolyte disturbances. Therefore, we investigated the association between altered calcium homeostasis and the risk of all-cause mortality in chronic heart failure patients.

METHODS

From Danish national registries, we identified patients with chronic heart failure with a serum calcium measurement within a minimum 90 days after initiated treatment with both loop diuretics and angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. Patients were divided into 3 groups according to serum calcium levels, and Cox regression was used to assess the mortality risk of <1.18 mmol/L (hypocalcemia) and >1.32 mmol/L (hypercalcemia) compared with 1.18 mmol/L-1.32 mmol/L (normocalcemia) as reference. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated.

RESULTS

Of 2729 patients meeting the inclusion criteria, 32.6% had hypocalcemia, 63.1% normocalcemia, and 4.3% hypercalcemia. The highest mortality risk was present in early deaths (≤30 days), with a HR of 2.22 (95% CI; 1.74-2.82) in hypocalcemic patients and 1.67 (95% CI; 0.96-2.90) in hypercalcemic patients compared with normocalcemic patients. As for late deaths (>30 days), a HR of 1.52 (95% CI; 1.12-2.05) was found for hypocalcemic patients and a HR of 1.87 (95% CI; 1.03-3.41) for hypercalcemic patients compared with normocalcemic patients. In adjusted analyses, hypocalcemia and hypercalcemia remained associated with an increased mortality risk in both the short term (≤30 days) and longer term (>30 days).

CONCLUSION

Altered calcium homeostasis was associated with an increased short-term mortality risk. Almost one-third of all the heart failure patients suffered from hypocalcemia, having a poor prognosis.

Vitamin D and Heart Failure

PURPOSE

Vitamin D is principally known for its role in calcium homeostasis, but preclinical studies implicate multiple pathways through which vitamin D may affect cardiovascular function and influence risk for heart failure. Many adults with cardiovascular disease have low vitamin D status, making it a potential therapeutic target. We review the rationale and potential role of vitamin D supplementation in the prevention and treatment of chronic heart failure.

RECENT FINDINGS

Substantial observational evidence has associated low vitamin D status with the risk of heart failure, ventricular remodeling, and clinical outcomes in heart failure, including mortality. However, trials assessing the influence of vitamin D supplementation on surrogate markers and clinical outcomes in heart failure have generally been small and inconclusive. There are insufficient data to recommend routine assessment or supplementation of vitamin D for the prevention or treatment of chronic heart failure. Prospective trials powered for clinical outcomes are warranted.

Effects of Vitamin D Supplementation on Renin and Aldosterone Concentrations in Patients with Advanced Heart Failure: The EVITA Trial

OBJECTIVE

1,25-Dihydroxyvitamin D (1,25([OH]₂D) is considered to be a negative endogenous regulator of the renin-angiotensin-aldosterone system (RAAS), but the effect of vitamin D supplementation on the RAAS is inconclusive.

DESIGN

In this prespecified secondary analysis of a randomized controlled trial, we assessed in 165 patients with heart failure (vitamin D group: n = 83; placebo group: n = 82) the effect of three years of vitamin D supplementation with 4000 IU daily on parameters of the RAAS (renin and aldosterone) and on circulating 1,25(OH)₂D, plasma phosphate, and fibroblast growth factor (FGF)-23. We assessed age- and baseline-adjusted between-group differences at study termination.

RESULTS

Almost all patients were under treatment with beta-blockers, inhibitors of the RAAS, and diuretics. Initially, the frequency of concentrations above the laboratory-specific reference range (renin: >23.9 mIU/L; aldosterone: >232 ng/L) in the vitamin D and placebo group was 87.7% and 92.7%, respectively (renin), and 24.1% and 32.5%, respectively (aldosterone). Vitamin D increased adjusted 1,25(OH)₂D concentrations significantly (mean treatment effect and 95% CI: 18.3 pmol/L,7.3 to 29.3 pmol/L; P < 0.001) but had no significant effects on phosphate (0.18 mmol/L, -0.00 to 0.35 mmol/L; P = 0.051), FGF-23 (685 RU/mL, -213 to 1585 RU/mL; P = 0.134), renin (312 mIU/L, -279 to 902 ng/L; P = 0.298), or aldosterone (-0.19 ng/L, -5.09 to 4.70 ng/L; P = 0.938). Vitamin D supplementation was, however, associated with an increase in renin concentrations in the subgroup with baseline 25-hydroxyvitamin D below 30 nmol/L (n = 67; 1365 mIU/, 343 to 2386 mIU/L; P = 0.010).

CONCLUSIONS

In patients with advanced heart failure treated according to evidence-based guidelines, vitamin D supplementation did not significantly influence parameters of the RAAS in the entire study cohort but was associated with an increase in plasma renin concentrations in the subgroup with low baseline 25-hydroxyvitamin D concentrations.

Serum Calcium and Risk of Sudden Cardiac Arrest in the General Population

OBJECTIVE

To evaluate the potential role of low serum Ca levels in the occurrence of sudden cardiac arrest (SCA) in the community.

PATIENTS AND METHODS

We compared 267 SCA cases [177 (66%) men] and 445 controls [314 (71%) men] from a large population-based study (catchment population ∼1 million individuals) in the US Northwest from February 1, 2002, through December 31, 2015. Patients were included if their age was 18 years or older with available creatinine clearance (CrCl) and serum electrolyte levels for analyses to enable adjustment for renal function. For cases, creatinine clearance and electrolyte levels were required to be measured within 90 days of the SCA event.

RESULTS

Cases of SCA had higher proportions of blacks [31 (12%) vs 14 (3%); P<.001], diabetes mellitus [122 (46%) vs 126 (28%); P<.001], and chronic kidney disease [102 (38%) vs 73 (16%); P<.001] than did controls. In multivariable logistic regression analysis, a 1-unit decrease in Ca levels was associated with a 1.6-fold increase in odds of SCA (odds ratio, 1.63; 95% CI, 1.06-2.51). Blood Ca levels lower than 8.95 mg/dL (to convert to mmol/L, multiply by 0.025) were associated with a 2.3-fold increase in odds of SCA as compared with levels higher than 9.55 mg/dL (odds ratio, 2.33; 95% CI, 1.17-4.61). Cases of SCA had significantly prolonged corrected QT intervals on the 12-lead electrocardiogram than did controls (465±37 ms vs 425±33 ms; P<.001).

CONCLUSION

Lower serum Ca levels were independently associated with an increased risk of SCA in the community.

Evaluation of two fully automated immunoassay based tests for the measurement of 1α,25-dihydroxyvitamin D in human serum and comparison with LC-MS/MS

BACKGROUND

1α,25-Dihydroxyvitamin D [1,25(OH)2 vitD] is the bioactive form of vitamin D. Due to the very low concentrations of 1,25(OH)2 vitD in the blood and its lipophilic character, measurement of this parameter is analytically challenging. Requiring preceding manual extraction steps before analysis, previous assays have been laborious.

METHODS

In the presented study, we evaluated the performance of two immunoassays from DiaSorin and from Immunodiagnostic Systems (IDS) which combine fully automated extraction and measurement of 1,25(OH)2 vitD. Imprecision and linearity were verified according to Clinical and Laboratory Standards Institute EP15-A3 and EP6-A guidelines, respectively. Ninety-three patient serum samples sent to our institute for determination of 1,25(OH)2 vitD, as well as 20 Vitamin D External Quality Assessment Scheme (DEQAS) samples, were used to evaluate correlation and agreement of 1,25(OH)2 vitD measurements between the two immunoassays and with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS).

RESULTS

Total imprecision was 5.2% or less for the DiaSorin test but reached 20.1% for the IDS iSYS test. 1,25(OH)2 vitD concentrations measured with the DiaSorin assay showed a strong correlation with 1,25(OH)2 vitD levels measured by LC-MS/MS and a good agreement with method specific means of DEQAS samples. By contrast, the IDS iSYS test overestimated 1,25(OH)2 vitD concentrations in human serum, particularly at higher concentrations.

CONCLUSIONS

Due to its high sensitivity, low imprecision, broad measurement range, and good agreement with 1,25(OH)2 vitD concentrations measured by LC-MS/MS, the DiaSorin test is a valuable analytical option for the determination of 1,25(OH)2 vitD.

The association of serum magnesium and mortality outcomes in heart failure patients: A systematic review and meta-analysis

BACKGROUND

Low serum magnesium (Mg) has been independently shown to increase risk of heart failure (HF), but data on the association between serum Mg concentration and the outcome of patients with HF are conflicting. The purpose of this systematic review and meta-analysis was to estimate the prognostic effects of hypermagnesemia and hypomagnesemia on cardiovascular (CV) mortality and all-cause mortality (ACM) of patients with HF.

METHODS

Relevant studies were identified from Medline and Scopus databases. Included and excluded criteria were defined. Effects (i.e., log [risk ratio [RR]]) of hypomagnesemia and hypermagnesemia versus normomagnesemia were estimated using Poisson regression, and then a multivariate meta-analysis was applied for pooling RRs across studies. Heterogeneity was explored using a meta-regression and subgroup analysis.

RESULTS

On analysis, 7 eligible prospective studies yielded a total of 5172 chronic HF patients with 913 and 1438 deaths from CV and ACM, respectively. Most participants were elderly men with left ventricular (LV) ejection fraction ≤40%. Those patients with baseline hypermagnesemia had a significantly higher risk of CV mortality (RR, 1.38; 95% confidence interval [CI], 1.07-1.78) or ACM (RR, 1.35; 95% CI, 1.18-1.54) than those with baseline normomagnesemia. However, baseline hypomagnesemia was not associated with the risk of CV mortality (RR, 1.11; 95% CI, 0.79-1.57) and ACM (RR, 1.11; 95% CI, 0.87-1.41). A subgroup analysis by Mg cutoff suggested a dose-response trend for hypermagnesemia effects, that is, the pooled RRs for CV mortality were 1.28 (95% CI, 1.05-1.55) and 1.92 (95% CI, 1.00-3.68) for the cutoff of 0.89 to 1.00 and 1.05 to 1.70 mmol/L, respectively.

CONCLUSION

The present systematic review and meta-analysis suggested that, in HF patients, hypermagnesemia with serum Mg ≥ 1.05 mmol/L was associated with an increased risk of CV mortality and ACM but this was not observed for hypomagnesemia. This finding was limited to the elderly patients with chronic HF who had reduced LV systolic function.

Calciotropic and phosphaturic hormones in heart failure

AIMS

Despite adherence to evidence-based guidelines, heart failure [HF] still results in 5-year mortality rates of 50%, indicating a need to implement additional preventive/intervention strategies. This review summarizes data on alterations in the calciotropic and phosphaturic hormones 1,25-dihydroxyvitamin D [1,25(OH)₂D] and fibroblast growth factors-23 [FGF-23] in HF and discusses non-pharmacological measures for targeting these hormones.

DATA SYNTHESIS

The role of 1,25(OH)₂D in the regulation of calcium and phosphate homeostasis is central. 1,25(OH)₂D also plays a pivotal role in cardiac function, but is downregulated by FGF-23. There is accumulating evidence from epidemiological data that HF is associated with decreased circulating 1,25(OH)₂D and elevated FGF-23 levels. In patients with failing hearts, very low 1,25(OH)₂D and extremely high FGF-23 levels have been reported. Experimental data support the assumption that vitamin D deficiency and high serum phosphate/FGF-23 levels increase the risk of HF. This review provides a hypothesis of how vitamin D deficiency, high calcium/phosphorus intake, physical inactivity, and age-related renal impairment may all contribute to HF by adversely affecting calcium- and phosphate-regulating hormones. Several case series in infants and a meta-analysis of randomized controlled trials in adults have already reported successful treatment of or a significant risk reduction in HF by vitamin D supplements. The association of calcium/phosphorus intake, physical activity, or renal function with calciotropic/phosphaturic hormones and HF is however less well documented.

CONCLUSIONS

More attention should be paid in future to the association of circulating 1,25(OH)₂D and FGF-23 levels with HF and to (non-pharmacological) measures for targeting these calciotropic/phosphaturic hormones.

Calciotropic and Phosphaturic Hormones in End-Stage Heart Failure Patients Supported by a Left-Ventricular Assist Device

Background

Calcium and phosphate are central for myocardial contractility and energy metabolism, and low levels of the calciotropic hormone 1,25-dihydroxyvitamin D (1,25(OH)₂D), as well as high levels of the phosphaturic hormone fibroblast growth factor (FGF)-23, are independently associated with poor clinical outcome in heart failure (HF) patients. We therefore aimed to investigate the postoperative time course of the aforementioned hormones in HF patients supported with a left-ventricular assist device (LVAD) implant.

Methods

For the present study, stored biobank plasma samples of 69 patients, collected before LVAD implantation (t0) and 12 days (t1), 30 days (t2), 83 days (t3), and 300 days (t4) post-intervention, were used to measure circulating FGF-23, parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), 1,25(OH)₂D, and kidney function.

Results

Most patients were male and had baseline INTERMACS levels and cardiac index values ≤ 3 and ≤ 2.7 L/min/m², respectively. There were significant time effects on estimated glomerular filtration rate (eGFR), FGF-23 and 1,25(OH)₂D, but not on PTH or 25OHD. Notably, eGFR values increased and FGF-23 levels decreased only transiently, whereas 1,25(OH)₂D increased continuously until t4. The rise in 1,25(OH)₂D was largely influenced by those patients who survived the first post-implant year, and was not seen in non-survivors. Variations in 1,25(OH)₂D levels could only partly be explained by eGFR values or FGF-23, 25OHD, and PTH levels (multiple R² = 0.305;P<0.001).

Conclusions

The present study indicates that LVAD implantation has only transient effects on circulating FGF-23 levels, but is associated with a continuous increase in circulating 1,25(OH)₂D levels, especially in survivors.

Measurement of Circulating 1,25-Dihydroxyvitamin D: Comparison of an Automated Method with a Liquid Chromatography Tandem Mass Spectrometry Method

Background. The clinical relevance of circulating 1,25-dihydroxyvitamin D (1,25(OH)₂D) is probably underappreciated, but variations in the measurement of this difficult analyte between different methods limit comparison of results. Methods. In 129 clinical samples, we compared a new automated assay with a commercially available liquid chromatography tandem mass spectrometry (LC-MS/MS) kit. Results. Median (interquartile range) 1,25(OH)₂D concentrations with the automated assay and the LC-MS/MS method were 26.6 pg/mL (18.5–39.0 pg/mL) and 23.6 pg/mL (16.1–31.3 pg/mL), respectively (P = 0.001). Using the method-specific cut-offs for deficient 1,25(OH)₂D levels (<20 pg/mL for the automated assay and <17 pg/mL for the LC-MS/MS method), the percentage of patients classified as 1,25(OH)₂D deficient was 28.7% and 27.1%, respectively. However, concordance between the two methods for deficient levels was only 62% and the concordance correlation coefficient was poor (0.534). The regression equation resulted in an intercept of −1.99 (95% CI: −7.33–1.31) and a slope of 1.27 (95% CI: 1.04–1.52) for the automated assay. The mean bias with respect to the mean of the two methods was −3.8 (1.96 SD: −28.3–20.8) pg/mL for the LC-MS/MS method minus the automated assay. Conclusions. The two methods show only modest correlation and further standardization is required to improve reliability and comparability of 1,25(OH)₂D test procedures.

FGF23 in Acute and Chronic Illness

FGF23 is a bone-derived phosphaturic hormone that may become a useful biomarker for the identification of high-risk patients in chronic but also acute disease. It rises early in chronic kidney disease and is strongly and independently associated with excess morbidity and mortality. Emerging data suggest that FGF23 is also elevated in different scenarios of acute illness. In this review, we give an overview on the role of this interesting disease marker and potential and proven interventional strategies and discuss a blueprint for future research.

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

BACKGROUND

Chronic 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 RESULTS

We 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).

CONCLUSIONS

Hypocalcemia was an independent predictor of all-cause mortality in HF and CKD patients.

Vitamin D metabolites and fibroblast growth factor-23 in patients with left ventricular assist device implants: association with stroke and mortality risk

PURPOSE

Stroke and mortality risk in patients with left ventricular assist device (LVAD) implants continue to be high. Whether nonclassical cardiovascular risk markers such as vitamin D metabolites and fibroblast growth factor (FGF)-23 contribute to this risk remains to be studied, and this was the objective of our work.

METHODS

In 154 LVAD patients (91 HeartWare and 63 HeartMate II implants), we measured circulating 25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D3 (1,25[OH]2D3), parathyroid hormone (PTH) and FGF-23 shortly before LVAD implantation and investigated their association with stroke and mortality risk during 1-year follow-up.

RESULTS

Of the study cohort, 34.4 and 92.2%, respectively, had deficient 25OHD (<25 nmol/l) and 1,25(OH)2D3 (<41 pmol/l) values, whereas 42.6 and 98.7%, respectively, had elevated PTH levels (>6.7 pmol/l) and FGF-23 values above the reference range (100 RU/ml). One-year freedom from stroke was 80.9 %, and 1-year survival was 64.3%. The multivariable-adjusted hazard ratio of stroke was 2.44 (95% CI: 1.09-5.45; P = 0.03) for the subgroup of 25OHD levels <25 nmol/l (reference group: 25OHD levels ≥25 nmol/l). The multivariable-adjusted hazard ratio of 1-year mortality was 2.78 (95% CI: 1.52-5.09; P = 0.001) for patients with 25OHD levels <25 nmol/l compared with patients with 25OHD levels ≥25 nmol/l. PTH, FGF-23 and 1,25(OH)2D3 were not associated with stroke or mortality risk.

CONCLUSIONS

In LVAD patients, deficient 25OHD levels are independently associated with high stroke and mortality risk. If confirmed in randomized controlled trials, preoperative correction of deficient vitamin D status could be a promising measure to reduce stroke and mortality risk in LVAD patients.

Roles of phosphate and fibroblast growth factor 23 in cardiovascular disease

Disturbances in phosphate homeostasis are common in patients with chronic kidney disease. As kidney function declines, circulating concentrations of phosphate and the phosphate-regulatory hormone, fibroblast growth factor (FGF)-23, rise progressively. Higher serum levels of phosphate and FGF-23 are associated with an increased risk of adverse outcomes, including all-cause mortality and cardiovascular events. The associations between higher FGF-23 levels and adverse cardiovascular outcomes are generally independent of serum phosphate levels, and might be strongest for congestive heart failure. Higher serum phosphate levels are also modestly associated with an increased risk of cardiovascular events even after accounting for FGF-23 levels. This observation suggests that FGF-23 and phosphate might promote distinct mechanisms of cardiovascular toxicity. Indeed, animal models implicate high serum phosphate as a mechanism of vascular calcification and endothelial dysfunction, whereas high levels of FGF-23 are implicated in left ventricular hypertrophy. These seemingly distinct, but perhaps additive, adverse effects of phosphate on the vasculature and FGF-23 on the heart suggest that future population-level and individual-level interventions will need to simultaneously target these molecules to reduce the risk of associated cardiovascular events.

Calcium, phosphate and calcium phosphate product are markers of outcome in patients with chronic heart failure

BACKGROUND

Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF).

METHODS

Unselected, consecutive patients with CHF (left ventricular ejection fraction, LVEF ≤45%) were enrolled in a prospective observational study for the occurrence of hospitalisation and mortality. Blood samples were collected at the time of recruitment and analysed immediately.

RESULTS

Patients (n = 713) were on contemporary optimal treatment and mean (standard error, SE) follow-up was 765 (18.9) days. Mean (SE) Ca was 2.29 (0.004) mmol/l. Median (interquartile range, IQR) Pi was 1.11 (0.98-1.23) mmol/l and median CPP 2.53 (2.21-2.88) mmol(2)/l(2). LVEF correlated inversely with Ca, natural log-transformed (Ln)Pi, and LnCPP. There was no difference in CPP between classes of symptom severity or diabetes status. Ca and LnCPP (but not LnPi) were associated with total mortality. Ca was significantly associated with progressive HF and non-cardiovascular death but not with sudden death. Binary logistic regression analyses showed that LnPi and LnCPP were associated with risk of hospitalisation.

CONCLUSIONS

Ca, Pi and CPP could be useful additional variables in determining risk in CHF patients. Further work is required to elucidate the mechanisms underlying the adverse influence and determine whether lowering phosphate levels per se in CHF patients is of benefit.

Future directions in vitamin D and cardiovascular research

AIMS

Evidence is accumulating that vitamin D status may influence the risk of cardiovascular disease (CVD). Final confirmation for a causal relationship between vitamin D and CVD is however still lacking. The present viewpoint article outlines several future research directions to close this gap.

DATA SYNTHESIS

Future directions include the need of performing large randomised controlled supplementation trials with vitamin D in specific risk groups. In addition, large register sets of data on vitamin D supplementation can be used, provided that adequate statistical methods such as propensity score modelled analysis are applied. To better understand vitamin D-mediated effects on CVD risk, the routine measurement of circulating levels of the hormonal vitamin D form, 1,25-dihydroxyvitamin D, is also necessary, in addition to the determination of its precursor 25-hydroxyvitamin D. Further, genetic association studies may help in clarifying the contribution of vitamin D to the development of CVD. Finally, the interrelationship of vitamin D with physical activity should be considered when studying CVD risk.

CONCLUSIONS

Overall, it can be expected that the next 10-15 years will provide an increased clarity concerning the role of vitamin D in CVD.