risk stratification in an etiologically and functionally inhomogeneous group of heart failure ( hf ) patients is an important element for management from both a medical and an economic point of view . accurate identification of patients who are most likely to benefit from heart transplantation is imperative due to an organ shortage and perioperative complications [ 1 , 2 ] . there are several risk stratification models that can be used to predict the prognosis of patients with hf . the first is aaronson 's scale , which consists of such clinical data as resting heart rate , left ventricular ejection fraction , mean blood pressure , interventricular conduction defects , serum sodium , mean wedge pressure , ischemic etiology of cardiomyopathy and assessment of peak oxygen consumption . the necessity for the assessment of peak oxygen consumption limits the possibility of using this model widely . in addition , changes in the medical treatment of hf since 1995 ( especially the widespread use of beta blockers ) and the predictive value of hemodynamic changes over time are not adequately taken into account in aronson 's stratification model [ 1 , 4 ] . the next prognostic scale is the cvm - hf , which was created by senni et al . in 2006 and includes : medications ( beta blockers , acei ) , nyha class iii / iv , left ventricular ejection fraction < 20% , severe valvular heart disease , atrial fibrillation and coexisting diseases ( anemia , arterial hypertension , chronic obstructive pulmonary disease , complicated diabetes mellitus , moderate to severe kidney dysfunction , metastatic cancer ) . this model was derived and validated in a single center with stable hf patients who were mostly undergoing optimal pharmacological treatment . the limitations of this model are that patients with preserved and impaired systolic function were included in the study group and the study group was relatively small . the seattle heart failure model ( shfm ) was constructed in 2006 by levy et al . it was developed in the praise-1 database and validated among patients participating in observational studies , clinical trials and registries ( elite-2 , val - heft , university of washington cohort , renaissance and italian heart failure registry ) . an shfm score is calculated based on 24 variables , including clinical characteristics ( gender , age , nyha class , weight , ischemic etiology , systolic blood pressure , left ventricular ejection fraction ) , laboratory data ( serum cholesterol , sodium and uric acid level , lymphocyte percentage , hemoglobin ) , medications and device therapy ( implantable cardioverter - defibrillator , cardiac resynchronization therapy ) . this model consists of a large number of parameters , such as commonly obtained baseline clinical data , medications and devices , which do not reflect the multiorgan dysfunction that is the essence of advanced heart failure . the next risk stratification scale , which was created in 2008 , is the munich score . this model contains five parameters : etiology of hf , systolic blood pressure , left ventricular end diastolic diameter , maximum workload and the change in the fractional shortening of the left ventricle over 12 months . this scale offers an efficient and non - invasive tool for pre - transplant risk stratification . univariate and multivariate analyses in this model show no statistical significance of elements of aronson 's scale such as heart rate at rest , serum sodium , intraventricular conduction defect or peak oxygen consumption . its main limitation is that the data came from a single center and this scale predicts a combined end point ( death and heart transplantation ) . the changes in medical treatment and device therapy of hf over time are not adequately taken into account in the above - mentioned stratification models . in addition , although a number of risk stratification scales have been established to assess risk in heart failure patients who are referred for heart transplantation evaluation , these models fail to adequately address the impact of liver dysfunction . abnormal liver function tests that reflect liver dysfunction are important indices of heart failure severity and higher risk of death . the pathophysiology of liver failure in heart failure has been attributed to venous congestion and reduced cardiac output that leads to hepatic congestion and hepatic low perfusion . low perfusion is less important than congestion because oxygen consumption can be increased when hepatic blood flow is decreased [ 10 , 11 ] . moreover , compared to other organs , the liver 's dual blood supply ( from the portal system and hepatic artery ) makes it relatively resistant to hepatocyte necrosis from haemodynamic instability [ 9 , 12 ] . for these reasons . a critical elevation of transaminases is observed only in cases of marked hypotension [ 10 , 13 ] . multiple studies have shown a decrease in serum total protein , albumin , coagulation factors and lipid levels and as a result cachexia and bleeding . most frequently , we can observe a mild increase in the serum bilirubin level ( in 30 - 70% of patients ) and an increased level of other cholestatic indices such as alkaline phosphatase or -glutamyltranspeptidase ( in 20% of patients ) [ 9 , 14 , 15 ] . several studies performed on heart failure patients have shown that serum bilirubin level correlates with hemodynamic parameters such as right atrial pressure , severity of tricuspid regurgitation , wedge pressure , left ventricular ejection fraction and the cardiac index [ 8 , 10 , 16 ] . two non - cardiac biomarkers which reflect the severity of the effect of hepatic dysfunction on metabolism ( total bilirubin ) and synthesis ( inr  international normalized ratio ) are elements of the classical model for end - stage liver disease ( meld ) score . therefore , the meld score system is a marker of multisystem dysfunction ( renal , cardiac , hepatic ) and coagulopathy . the meld was initially developed to assess mortality in subjects with cirrhosis who had undergone transjugular intrahepatic portosystemic shunt procedures [ 17 , 18 ] . in addition , it was validated as a predictor of survival in patients with end - stage liver disease . moreover , the clinical utility of meld was used to select patients who might profit from liver transplantation and to predict operative morbidity and mortality in cirrhotics undergoing cardiac and noncardiac procedures [ 19 , 20 , 21 ] . and ailavadi et al . observed dependence between the meld score and postoperative mortality in the group of non - cardiac cirrhotic patients undergoing non - transplant procedures [ 22 , 23 ] . meld is currently applied to determine the prognosis of patients with chronic heart failure who are referred for mechanical circulatory support or heart transplantation [ 24 , 25 ] . matthews et al . analyzed patients from the intermacs ( interagency registry of mechanically assisted circulatory support ) registry and the umhs ( university of michigan health system ) mechanical circulatory support database . these authors demonstrated that preoperative meld scores can identify left ventricular assist device candidates who are at high risk for perioperative bleeding and mortality . this analysis showed an increased frequency of postoperative device infections and renal failure in patients who required many perioperative transfusions . the association between the meld score and renal failure is due to the fact that creatinine is a part of the meld model . the association between the meld score and infection may be related to bacterial exposures during prolonged intensive care unit and total hospital stays . in addition , matthews et al . have demonstrated an increased frequency of right ventricular failure in patients with higher meld scores . the reason cited for this was that blood transfusions can increase the right ventricular preload and provoke the release of cytokines which then cause respiratory insufficiency and pulmonary hypertension . many transfusions also increase risk of allosensitization , which is associated with a worse outcome in patients after heart transplantation . retrospectively analyzed patients before and after heart transplantation and assessed the serum levels of hepatic function tests and meld scores . the percentage of patients with a pathologic serum level of hepatic function markers decreased significantly after heart transplantation . the authors confirmed that liver dysfunction was associated with higher rates of postoperative complications and an impaired prognosis in patients undergoing orthotopic heart transplantation . they concluded that higher meld scores can identify patients who are at a higher risk for complications and reduced survival after heart transplantation . the meld score may not be a valid prognostic index in patients who are undergoing warfarin therapy because warfarin affects the international normalized ratio ( inr ) . an alternative meld scale that omits inr , which can be used for patients undergoing anticoagulant therapy , was created by heuman et al . . the authors confirmed that a modified meld score , meld - xi ( meld excluding inr score ) , which is calculated based on two parameters , bilirubin and creatinine , was a predictor of pretransplant mortality in cirrhotic patients . adopted the meld - ix score to determine disease severity and to predict mortality in patients who were undergoing fontan surgery . they concluded that patients with a higher meld - xi score have higher risk of death and cardiac transplantation . tsuda et al . excluded the inr variable from the meld score and created a simplified model which only used total bilirubin and creatinine . the authors assessed the ability of this scale to predict mortality for patients who were undergoing tricuspid valve surgery . this analysis demonstrated that the simplified meld score was an independent risk factor for hospital mortality and morbidity . choshi et al .   used a modified meld score that replaced inr with albumin levels to substitute for the impaired production of coagulation factors of prothrombin complex with albumin . the substitution of inr with albumin was based on the fact that both are indicators of secretory liver function . the modified meld score correlates with the standard score and is better than the standard score due to the lack of an interaction with oral anticoagulants . elevated modified meld scores before heart transplantation were associated with worse morbidity and mortality after the operation . kim et al . evaluated the meld score and its modifications in predicting survival and endpoint ( death , heart transplantation , ventricular assist device implantation ) in a group of end - stage heart failure patients who were undergoing a cardiac transplantation evaluation . they compared the prognostic value of meld , meld - xi and meld - na in patients who were either on or off anticoagulant treatment . meld - na consisted of the bilirubin and creatinine levels , inr ratio and the sodium level , which is an important marker of mortality . the authors found that meld was a good predictor of a worse outcome and that the presence of serum sodium in the meld scale resulted in an improved prognostic strength . being treated with anticoagulation , meld - xi was a prognostic factor of the necessity of heart transplantation . meld - xi had a worse prognostic strength in patients being treated with oral anticoagulation compared with patients who were not receiving anticoagulation therapy . the reason for this could be the fact that patients receiving anticoagulation have multiple comorbidities which are risk factors of poorer outcome . in conclusion , the aaronson and seattle scales that were previously used widely demonstrated a high prognostic value in ambulatory patients with stable heart failure . the predictive value of aaronson 's scale is less reliable today than it used to be due to the changes in the guidelines on the management of heart failure . the meld scale and its modifications are better in terms of a prognostic index in patients with advanced heart failure than previous models because they take into account multiorgan failure , which is the essence of this pathological state . a good option is to use the meld - xi scale combined with other prognostic models for patients who need oral anticoagulation .
risk stratification in heart failure ( hf ) patients is an important element for management . 
 there are several risk stratification models that can be used to predict the prognosis of patients with hf , such as aaronson 's scale , cvm - hf ( cardiovascular medicine heart failure ) , the seattle heart failure model ( shfm ) and the munich score . 
 these models fail to adequately address the impact of multiorgan dysfunction on prognosis . the classical model for end - stage liver disease ( 
 meld ) score consists of : total bilirubin , inr ( international normalized ratio ) and creatinine level . 
 there are some modifications of the meld scale : meld - xi , which excludes the inr score ; the mod - meld score , in which inr is replaced with albumin levels ; and meld - na , which consists of the bilirubin and creatinine levels , inr ratio and the sodium level . 
 therefore , the meld score systems are markers of multisystem dysfunction ( renal , cardiac , hepatic ) . 
 it is important that they are composed of routinely collected laboratory measures which are easy to use .