The Clinical Significance And Reasons Of Low T3 Syndrome In Patients With Chronic Heart Failure

BackgroundChronic heart failure(CHF),is a clinical syndrome characterized by typical symptoms(e.g.breathlessness,ankle swelling and fatigue)that may be accompanied by signs(e.g.elevated jugular venous pressure,pulmonary crackles and peripheral oedema)caused by a structural and/or func-tional cardiac abnormality,resulting in a reduced cardiac output and/or elevated intracardiac pressures at rest or during stress.The incidence of chronic heart failure is increasing with the aging of the population,the increasing of hypertension and coronary heart disease and the increased survival rate of acute myocardial infarction,and has become a major global public health problem.In terms of 5-year survival rates,CHF is even lower than many malignant neoplastic diseases.The World Health Organization has predicted that by 2020,cardio-cerebrovascular disease will become the world's first cause of death and disability,the form is not optimistic.The pathological changes of heart failure are the activating of renin-angiotensin-aldosterone system(RAAS)system,the increasing of sympathetic excitability,and the changing in humoral factors(including arginine vasopressin,natriuretic peptide,endothelin,cytokines,etc.).In recent years,domestic and foreign scholars have found that patients with chronic heart failure often accompanied by low T3 syndrome,also known as euthyroid sick syndrome.Low T3 syndrome mainly manifested as TSH is normal,FT3 and T3 are reduced,FT4 and T4 are normal or mild reduced.A number of studies have shown that patients with chronic heart failure often accompanied by low T3 syndrome,and the severity of heart failure is closely related to the level of FT3.However,there are few studies on the causes and prognosis of low T3 syndrome in patients with chronic heart failure.This study aims to further explore the correlation between low T3 syndrome and the severity of chronic heart failure,and analyze the causes of low T3 syndrome in patients with chronic heart failure and the significance of prognosis in patients with heart failure.The study is divided into two parts.Part1 The correlation between Low T3 syndrome and the severity of Chronic Heart FailureObjectives To sdudy the serum thyroxine levels in patients with chronic heart failure and the correlation between low T3 syndrome and the severity of chronic heart failure.Objects 338 cases of 60-80years old patients suffering from CHF who hospitalized in Cardiovascular Department of our hospital from January 2014 to April 2015 were collected(including acute exacerbation of chronic heart failure).Excluding thyroid disease,severe liver and kidney disease,COPD,cancer,systemic immune disease,recently taking amiodarone and other serious chronic diseases.According to the New York Heart Association(NYHA)classification,NYHA ?11 Ocases,NYHA ?122cases,NYHA ? 106cases.In addition,210 cases of healthy persons from examination center of our hospital in the same period were selected as control group.Methods Compared the differences of thyroid hormone and general clinical data between heart failure group and control group,between different levels of cardiac function.And analyze the relationship between FT3,T3 levels and cardiac function.Results(1)There is no significant difference in gender,age,BMI between heart failure group and control group(P>0.05);The serum T3 and FT3 levels of heart failure group were lower than control group(P<0.01);the differences of T4,FT4,TSH in the two groups have no statistical significance(P?0.05).(2)The differences of age,gender,BMI between NYHA class ?,?,? have no statistical significance(P>0.05);The levels of T3 and FT3 between NYHA class?,?,? have statistical significance(P<0.01),and the levels decrease with the elevate of NYHA classification;T4,FT4,TSH have no significant differences between different levels of cardiac function(P>0.05).(3)The levels of FT3 and T3 in patients with heart failure were negatively correlated with NT-proBNP(r=-0.673,P<0.01;r=-0.623,P<0.01)and cardiac function classification(r=-0.605,P<0.00;r=-0.534,P<0.01),positively correlated with LVEF(r=0.607,P<0.01;r=0.531,P<0.01).Conclusions(1)Thyroid hormone metabolic disorders which exist in patients with chronic heart failure manifested as levels of T3,FT3 decreased,and the levels decrease with the elevate of NYHA classification;T4,FT4,TSH have no significant differences between different levels of cardiac function.(2)The levels of T3,FT3 was closely related to the severity of heart failure.T3 and FT3 can be used to evaluate the severity of heart failure.Part 2 The prognosis and reasons of low T3 syndrome in patients with chronic heart failureObjectives We sought to assess whether low T3 syndrome could have prognostic impact in patients with chronic heart failure and analysis the reasons why patients with chronic heart failure often accompanied by low T3 syndrome.Objects The objects are the 338 cases of patients in the part 1,which lost 128 cases,the final group is 210 cases.According to the New York Heart Association(NYHA)classification,NYHA? 67cases,NYHA ? 77cases,NYHA? 66cases.Methods Divide the patients with heart failure into low T3 syndrome group and normal group according to the level of FT3,compared the differences between two groups in hospital mortality,six months rate of rehospitalization,and one year mortality rate.Furthermore,the multiple stepwise regression analysis was applied to explore the possible causes of low T3 syndrome in patients with heart failure,with FT3 level as the dependent variable,age,sex,BMI,serum albumin,hemoglobin,CRP,triglyceride,total cholesterol,high density lipoprotein,low density lipoprotein as the independent variables.Results(1)The hospital mortality,six months rate of rehospitalization,and one year mortality rate of low T3 group are higher than that of the normal group(x2=20.139,P<0.01;x2=5.711,P<0.05;x2=5.037,P<0.05).(2)The results of multiple linear regression analysis showed that serum albumin and CRP were related to the level of FT3,the regression equation is Y=0.254+0.067(ALB)-0.012(CRP).Conclusions(1)The levels of T3,FT3 was closely related to the prognosis of heart failure.T3 and FT3 can be used to evaluate the prognosis of heart failure.(2)Low T3 syndrome in patients with heart failure may be associated with the decrease of serum albumin and elevate of inflammatory cytokines,such as CRP.