Frailty and MECKI score in predicting mortality in advanced heart failure

Abstract Background Physical frailty (PF), characterized by decreased physiological reserves and increased vulnerability to stressors, has emerged as a significant predictor of adverse outcomes in heart failure (HF). The MECKI (Metabolic Exercise Cardiac Kidney Index) score, a composite index derived from cardiopulmonary exercise testing parameters and renal function, has shown promise in predicting outcomes in HF patients. Purpose The aim of the study is to evaluate the independent prognostic role of the MECKI score and PF on mortality in patients with advanced heart failure (AHF). Methods Ninety-one patients with AHF were enrolled, including 42 on the heart transplant waiting list, 10 undergoing evaluation for listing, and 49 removed from the list due to transplant contraindications or reaching age limits. All patients included in the study were on medically optimized therapy. MECKI score assessment was conducted upon enrollment, along with hematological and biochemical evaluations including creatinine, hemoglobin, Na+, and NT-pro-BNP levels. Patients also underwent echocardiography assessing ejection fraction (EF), TAPSE, Inferior Vena Cava (IVC) diameters, and PASP. Additionally, all patients performed the 6-minute walk test (6MWT) and cardiopulmonary exercise testing with assessment of VO2max and VE/VCO2. Frailty was assessed based on modified Fried criteria. Results The mean age was 56.5±11.2 years. Mean NYHA class was 2.7±0.6, EF was 28.8±7.6, TAPSE was 17.5±4.2, and NT-proBNP was 2912.2±3249.0. Mean VO2max was 12.0±3.5 ml/kg/min, and mean distance walked during 6MWT was 278.8±137.2 meters. Mean frailty score was 3.2±1.2 while mean MECKI score was 15.2±14,2. During a mean follow-up of 32.0±15.3 months, there were 21 deaths, 15 patients received heart transplants, and 1 patient underwent LVAD implantation. Stratified data for mortality showed statistically significant differences in deceased patients compared to survivors regarding NYHA class (3.2±0.3 vs 2.6±0.7; p<0.001), Frailty Index (4.4±0.7 vs 2.7±1.13; p<0.001), NT-proBNP (5425.0±2863.0 vs 1731.0±1618.0; p<0.001), VE/VCO2 (42.7±12.3 vs 35.0±9.1; p<0.003), and MECKI score (29.4±15.2 vs 11.2±11.2; p<0.001). Linear regression analysis demonstrated a significant positive correlation for Frailty Index and MECKI score with age, NYHA class, VE/VCO2, IVC, and NT-proBNP, while showing a negative correlation with TAPSE, VO2max, and 6-minute walk test. Cox regression analysis on mortality demonstrated the predictive role of Frailty (HR=2.121; 95%CI=1.017-4.421; p=0.045) and MECKI score (HR=1.043; 95%CI=1.009-1.079; p=0.014) independently from age, sex, NYHA class, NT-proBNP, EF, TAPSE, VO2max, 6MWT, and IVC diameter. ROC curves demonstrated an AUC of 0.896 for MECKI score and mortality, and 0.884 for Frailty Index and mortality. Conclusions The MECKI score and physical frailty are both valid independent predictors of mortality in patients with advanced heart failure.