Leg muscle strength at discharge predicts rehospitalization risk in VAD implantees

In patients with newly implanted ventricular assist devices (VAD), better leg extensor muscle strength (LEMS) at discharge may suggest a lower risk of rehospitalization, according to a recent Japan study.

“Grip strength is an indicator of muscle strength. However, in cardiac surgery patients, upper limb muscle training interventions have not been implemented in daily clinical practice because of the need to avoid unwanted bone adhesion,” the researchers said.

In this study, the researchers considered lower limb muscle strength an indicator of the improvement potential of VAD patients. Leg muscle strength correlated with readmission and thus could be a target for rehabilitation.

Twenty-eight patients with new VAD implants were enrolled, all of whom had been discharged for 1 year. Using a handheld dynamometer, patients were divided into two groups according to median LEMS: high strength (group H; LEMS ≥55.2 kgf/body weight [BW]; n=14) and low strength (group L; LEMS <55.2 kgf/BW; n=14). Twelve patients were rehospitalized within 1 year of discharge, yielding a rate of 42.9 percent. [Sci Rep 2022;12:50]

The most common reason for rehospitalization was infection, which was detected in six patients, followed by bleeding (n=3), dislocation (n=2), and heart failure (n=1). Rehospitalization due to adverse events occurred more frequently in group L than H (64.3 percent vs 21.4 percent; log-rank p=0.02).

In contrast, physical function did not differ between patients who were vs were not rehospitalized. Age (p=0.25), body mass index (p=0.944), left ventricular ejection fraction (p=0.564), C-reactive protein (p=0.475), serum creatinine (p=0.835), and brain natriuretic peptide levels (p=0.805) did not differ between the H and L groups.

The same was true for other measures of physical function or muscle strength such as the 6-min walking distance (6MWD; p=0.296), grip strength (p=0.919), and peak oxygen intake (p=0.956). No deaths were reported.

“Muscle weakness involves insufficient protein synthesis; thus, our patients with low muscle strength may have had a higher rate of readmission due to both the lack of vigorous resistance training and protein synthesis,” the researchers said.

Indeed, the 16 patients who avoided rehospitalization showed significant improvements in physical function during the 1 year after discharge. Grip strength, for instance, increased from 48.6 kgf/BW at discharge to 56.3 kgf/BW 1 year after (p=0.011). The same was true for maximum oxygen intake (p=0.002) and 6MWD (p<0.001).

“To maintain quality of life, patients must maintain their physical function. Therefore, clinicians should be attentive to physical function when patients are hospitalized,” the researchers said. “Because the LEMS of VAD patients is unlikely to increase after discharge, it is important to focus on cardiac rehabilitation during hospitalization with the goal of attaining adequate LEMS.”

“Further research is warranted to explore the potential for strength recovery of VAD patients, according to the researchers.