Enhanced Echo Intensity of Skeletal Muscle Is Associated With Exercise Intolerance in Patients With Heart Failure

Background: Skeletal muscle is quantitatively and qualitatively impaired in patients with heart failure (HF), which is closely linked to lowered exercise capacity. Ultrasonography (US) for skeletal muscle has emerged as a useful, noninvasive tool to evaluate muscle quality and quantity. Here we investigated whether muscle quality based on US-derived echo intensity (EI) is associated with exercise capacity in patients with HF.

Methods and results: Fifty-eight patients with HF (61 ± 12 years) and 28 control subjects (58 ± 14 years) were studied. The quadriceps femoris echo intensity (QEI) was significantly higher and the quadriceps femoris muscle thickness (QMT) was significantly lower in the patients with HF than the controls (88.3 ± 13.4 vs 81.1 ± 7.5, P= .010; 5.21 ± 1.10 vs 6.54 ±1.34 cm, P< .001, respectively). By univariate analysis, QEI was significantly correlated with age, peak oxygen uptake (VO₂), and New York Heart Association class in the HF group. A multivariable analysis revealed that the QEI was independently associated with peak VO₂ after adjustment for age, gender, body mass index, and QMT: β-coefficient = -11.80, 95%CI (-20.73, -2.86), P= .011.

Conclusion: Enhanced EI in skeletal muscle was independently associated with lowered exercise capacity in HF. The measurement of EI is low-cost, easily accessible, and suitable for assessment of HF-related alterations in skeletal muscle quality.