Skeletal Muscle Strength in Patients on the Heart Transplant Waiting List: Are There Any Associations with Instrumental Examination Data?

Background: Peripheral muscle dysfunction in chronic heart failure (CHF) potentiates hemodynamic insufficiency through neuroendocrine activation and deterioration of myocardial perfusion. Objectives: The aim of this study was to compare skeletal muscle strength in patients on the heart transplant (HT) waiting list and in patients undergoing cardiac surgery and to identify associations between muscle status and clinical and instrumental parameters. Methods: This study included 152 patients divided into two groups: Group I (n = 30)-candidates for HT; Group II (n = 122)-patients undergoing cardiac surgery. A comprehensive clinical and anamnestic assessment and instrumental diagnostics were performed. Muscle status was assessed using a Lafayette MMT01165 isokinetic dynamometer (knee and foot extensor/flexor strength) and a DK 100 dynamometer (handgrip strength). Echocardiographic parameters were assessed in the study groups; in the HT group, cardiac catheterization and volumetric sphygmography data were used. Results: Group HT had a higher proportion of men (p = 0.042) and a higher revascularization rate (p ≤ 0.027) compared with Group II. Patients in Group I had enlarged left and right heart diameters and critically low left ventricular ejection fraction (LVEF) (22%; p < 0.001). Group HT showed a significant decrease in lower extremity muscle strength compared with Group II (p < 0.001). The only independent predictors of knee extensor muscle strength were echocardiographic parameters (right atrial volume index, TAPSE, and LVEF/end diastolic volume). No association was found between knee extensor strength and the strength of other muscle groups studied. Conclusions: Patients on the HT waiting list had significant lower extremity muscle weakness compared with preoperative patients. The only independent predictors of knee extensor muscle strength were echocardiographic parameters. Knee extensor muscle strength was associated only with contralateral muscle strength, but not with other muscle groups. These results will facilitate the development and evaluation of personalized rehabilitation programs for patients on the heart transplant waiting list.