The Impact Of FGF23and Klotho Protein On Senile Degenerative Heart Valvular Disease And Related Risk Factors Analysis

Background and Objective:Senile degenerative heart valvular disease (SDHVD) is also known as senile heart calcific valvular disease. The morbidity of SDHVD increases with age, and the valvular stenosis aggravate with disease duration. SDHVD is associated with an increased risk of cardiovascular events and mortality in the elderly which can leads to cardiac morphological changes and dysfunction, cardiac hemodynamics disorder and severe cardiovascular complication. With the arriving of aging society the incidence and prevalence of SDHVD is exponentially increasing in China. Valvular calcification mainly involves left heart valve, in which aortic valve is the most common one, followed by the mitral valve. The pathological feature of SDHVD encompass deposition of lipid and collagen in valve and infiltration by inflammatory cells such as T lymphocytes and macrophage, and the valve interstitial cells who adopt an osteoblast-like phenotype leading to calcium accumulation are also evident. The mechanisms of SDHVD are still unclear. Previously, SDHVD was thought to be a chronic degenerated process with aging, but some studies recently indicate that valvular calcification may be a multiple-factors involved and active process which valve tissues react to some initiative factors. Klotho is a gene associated closely with aging, which plays an important part in maturation of body and health. Klotho-deficient mice show some symptoms similar to aging such as atherosclerosis, ectopic calcification, hypoglycemia and severe hyperphosphatemia. And these symptoms would ease when this gene re-express in mice. At present,the research of Klotho protein and senile degenerated heart valvular disease was few.Fibroblast growth factor23(FGF23) belongs to the polypeptide hormone family.It is a cytokine newly discovered in recent years involved in the metabolism of phosphorus. Klotho protein is closely related with FGF23. It is a key factor in FGF23signaling, Klotho proteins mediate FGF23to exert biological function. The studies concerning expression of Klotho protein and FGF23in SDHVD patients are sill rare.This study aim to analyze the expression of Klotho protein、FGF23and Lp(a) etc in SDHVD patients, investigate their role in valvular calcification. We followed up some patients in order to analyze the related factors influencing survival of patients.Part Ⅰ:Related risk factors analysis on senile degenerative valvular heart diseaseMethods:We identified253SDHVD patients of age45or above who hospitalized in the fisrt people’s Hospital of Foshan between June2012and July2013at random. The following cases were excluded in this study:(1) diagnosed as rheumatic heart disease with valvular stenosis;(2) diagnosed as congenital valve malformation;(3) valvular stenosis caused by infective endocarditis;(4) complicated with malignant tumor;(5) had radiotherapy at chest;(6) complicated with immunologic diseases (7) chronic hemodialysis patients (8) diagnosed as syphilis. Record related clinical data of all patients enrolled including sex, age, history of hypertension, diabetes,coronary heart disease and smoking; obtain vein blood sample for TCH, LDL-C, HDL-C, Lp(a) test. Caculate glomerular filtration rate(GFR) according to the MDRD formula eGFR (ml/min/173m2.)=170×[Scr]-0.999×(Age)-0.176×[Female×0.762]×[BUN]-0.17×[Alb]×0318.All patients enrolled underwent transthoracic echocardiographic examination to make clear the heart valve condition. According to the test results divide the patients into echocardiographic valvular calcification and without valvular calcification group. Criteria for determining heart valve calcification:valvular membrane or annulus become thickened in local site, echo become stronger, valvular leaflets opening range decreased. Statistical analysis was performed using the statistical package SPSS16.0. Continuous variables are expressed as mean±SD. We used Student’s t-test for differences between independent continuous variables. Whereas categorical data are described as percentages, and we used the χ2test to test for categorical variables. P value less than0.05was accepted as statistically significant. Multiple logistic regression analysis was used to evaluate the association between SDHVD and influence factors. Odds ratios were calculated.Result:1. The incidence of simple aortic valvular calcification is the highest in SDHVD group,91cases(81.98%), followed by the incidence of aortic valvular calcification combining mitral valvular calcification,17cases(15.32%).3cases have simple mitral valvular calcification.Tricuspid valvular calcification and pulmonary valvular calcification were not found.2. There were111patients with valvular calcification,69patients with simple valvular regurgitation,12patients with valvular regurgitation and valvular stenosis,4 patients with simple valvular stenosis.The proportion of simple valve regurgitation in SDHVD group is the highest(62.16%), all valve stenosis were aortic valvular calcification, mitral stenosis were not found in patients with mitral valvular calcification.3. There were no significant differences between SDHVD group and non-SDHVD group in sex, coronary heart disease, hypertension, diabetes, smoking, TCH, TG, LDL-C, HDL-C and uric acid(p>0.05). There were significant differences in Lp(a)(372.82±418.87mg/Lvs256.92±317.89mg/L,p=0.018), age(73.39±8.76years vs69.81±9.42years, p=0.002) and eGFR(58.33±19.10ml/min vs68.08±19.59ml/min, p=0.000) between two groups.4. Multivariate logistic regression analysis demonstrated that age, Lp(a) and eGFR were the risk factors of SDHVD (OR=1.038β=0.037p=0.030, OR=1.001β=0.001p=0.014and OR=0.983β=-0.017p=0.027, respectively).Conclusion:Degenerative heart valvular disease is mainly involved with aortic and mitral. The incidence of simple aortic valvular calcification is the highest in SDHVD,followed by the incidence of aortic valvular calcification combining mitral valvular calcification. The Lp(a) was higher in SDHVD group than in non-SDHVD group. Lp(a) is a risk factor for SDHVD. Increase of Lp(a) can increase the risk of heart valvular calcification. Age also is a risk factor for SDHVD, This study shows that for each increase of1year of age, the incidence of SDHVD increased the risk of a1.038-fold. GFR was lower in SDHVD group than in non-SDHVD group.eGFR is a risk factor for SDHVD. Decreasing of GFR increase the incidence risk of SDHVD. Part Ⅱ:The levels of serum FGF23and Klotho protein on senile degenerative heart valvular diseaseIn the first part we confirmed age,lipoprotein(a) and eGFR were the risk factors for SDHVD. But the levels of Klotho protein, FGF23in patients with SDHVD were not clear yet. Therefore,we analyzed the expression of Klotho protein and FGF23in SDHVD patients, investigated their role in valvular calcification.Methods:We identified71SDHVD patients of age50or above who hospitalized between August2012and April2013at random. The following cases were excluded in this study:(1) diagnosed as rheumatic heart disease with valvular lesions;(2) diagnosed as congenital valve malformation;(3) valvular stenosis caused by infective endocarditis;(4) complicated with malignant tumor;(5) had radiotherapy at chest;(6) complicated with immunologic diseases (7) chronic hemodialysis patients;(8) diagnosed as syphilis;(9) Acute myocardial infarction.Record related clinical data of all patients enrolled including sex, age, history of hypertension, diabetes,coronary heart disease and smoking; obtain vein blood sample for calcium, phosphorus, iPTH, hs-CRP test. Calculate GFR with MDRD formula; obtain blood sample to detect the level of Klotho and FGF23by ELISA. All patients enrolled underwent transthoracic echocardiographic examination to make clear the heart valve condition. According to the test results divide the patients into echocardiographic valvular calcification and without valvular calcification group. Statistical analysis was performed using the statistical package SPSS16.0. Continuous variables are expressed as mean±SD. We used Student’s t-test for differences between independent continuous variables and the χ2test to test for categorical variables. P value less than0.05was accepted as statistically significant.Result: 1. There were39patients with SDHVD.There were no significant differences in coronary heart disease, hypertension, diabetes and smoking between SDHVD group and non-SDHVD(p>0.05).There were significant differences in age(73.67±7.88years vs69.41±8.40years, p=0.031) between two groups.2. There were no significant differences in and the level of Klotho protein, calcium, phosphorus and iPTH between SDHVD group and non-SDHVD group(P>0.05).3. There were significant differences in the level of hs-CRP(19.06±31.23mg/L vs5.06±7.23mg/L,P=0.010) between two groups.4. There were significant differences in the level of FGF23(85.43±128.92pg/ml vs11.82±25.43pg/ml, P=0.001) between two groups. When stratified by age, the SDHVD group had a higher lever of FGF23(P<0.05). And when stratified by glomerular filtration rate the lever of FGF23was still higher in SDHVD group(P<0.05).5. The level of FGF23was not associated with the level of Klotho protein, calcium, phosphorus and iPTH.Conclusion:The levels of FGF23and hs-CRP in patients with SDHVD were significant higher than in non-SDHVD. There were no significant differences in the level of Klotho protein, calcium, phosphorus and iPTH between two groups. The level of FGF23was not associated with the level of Klotho protein, calcium, phosphorus and iPTH. FGF23may be involved in the process of the SDHVD, whose mechanism may be independent of the FGF23/Klotho axis. Part Ⅲ:Survival analysis of the patients in senile degenerative heart valvular diseaseThe study in the second part showed the levels of FGF23and hs-CRP in patients with SDHVD were significantly higher than in non-SDHVD patients.But we do not know the survival of patients with SDHVD,and the factors affecting it. Therefore we followed up the patients to analyze the related factors influencing the survival of patients.Methods:The enrolled patients in Part Ⅱ were followed up for32weeks, mainly by telephone follow-up. In addition, get information about the disease process of re-hospitalized patients from hospital records and use death as end point. Statistical analysis was performed using the statistical package SPSS16.0. Survival curves were calculated by the Kaplan-Meier method, and comparison was performed by the log-rank test. A Cox proportional hazards regression model was used for the multivariable analysis of independent prognostic factors for survival. P value less than0.05was considered statistically significant.Result:1. The survival rate of non-SDHVD group in32weeks was100%, and the survival rate of SDHVD group was86.5%, there was significant difference between two groups(P=0.045).5patients died in the SDHVD group,4patients died of heart failure.2. A multivariate Cox regression model was used to analyze the association between survival and clinical parameter or molecular risk factor including age, hs-CRP, Klotho protein, FGF2, GFR, Lp(a). The hs-CRP, FGF23was identified as an independent prognostic factor for survival (RR=1.033P=0.004; RR=1.007P=0.048,respectively). Conclusion:The survival rate of SDHVD patients decreased.Heart failure was the leading cause of mortality in degenerative valvular heart disease.The hs-CRP, FGF23was identified as an independent prognostic factor for survival.Summary:In this study,we analyzed the expression of Klotho protein、FGF23and Lp(a) etc in SDHVD patients, investigated their role in valvular calcification. We followed up some patients in order to analyze the related factors influencing survival of patients.Now we summarize below:(1) Age and decrease of glomerular filtration rate can increase the risk of heart valvular calcification.(2) FGF23may be involved in the process of the SDHVD, whose mechanism may be independent of the FGF23/Klotho axis.(3) The survival rate of SDHVD patients decrease. Heart failure is the leading cause of mortality in degenerative valvular heart disease. The hs-CRP, FGF23was identified as an independent prognostic factor for survival.