Physical Frailty Versus the MECKI Score in Risk Stratification of Patients with Advanced Heart Failure: Simpler Measure, Similar Insights?

<b>Background/Objectives:</b> Frailty, a syndrome characterized by diminished physiological reserves and increased vulnerability to stressors, is a strong predictor of adverse outcomes in heart failure. The MECKI (Metabolic Exercise Cardiac Kidney Index) score, derived from cardiopulmonary exercise testing and renal function parameters, has demonstrated prognostic value in HF patients. This study aimed to evaluate the prognostic value of physical frailty on mortality in patients with advanced heart failure and to compare it directly with the MECKI score. <b>Methods:</b> A total of 104 patients with advanced HF receiving optimized guideline-directed medical therapy were prospectively enrolled. At baseline, all patients underwent clinical, echocardiographic, and laboratory assessment and CPET for MECKI score calculation. Physical frailty was assessed using a modified Fried phenotype tailored for HF. The composite endpoint comprised all-cause mortality, urgent heart transplantation, or LVAD implantation. <b>Results:</b> Over a mean follow-up of 30.0 ± 15.3 months, there were 25 deaths, 5 urgent heart transplants, and 1 LVAD implantation. Patients who experienced the composite outcome had significantly worse NYHA class, higher NT-proBNP, lower VO₂max, higher VE/VCO₂ slope, higher frailty, and higher MECKI score (all <i>p</i> < 0.001). Frailty was significantly correlated with all MECKI score components, as demonstrated by Spearman's rank correlation analysis. Both frailty (HR = 1.89; 95% CI 1.22-2.93; <i>p</i> = 0.005) and MECKI score (HR = 1.04; 95% CI 1.00-1.08; <i>p</i> = 0.037) independently predicted outcomes. ROC analysis showed high and comparable discriminative performance (AUC = 0.86 for frailty; AUC = 0.88 for MECKI). <b>Conclusions:</b> Physical frailty and MECKI scores independently predict mortality and adverse events in advanced HF. Physical frailty, despite its simplicity and low cost, provides prognostic insight comparable to the MECKI score and may represent a practical alternative when CPET is unavailable.