Heart failure-related myopathy - Clinical and pathophysiological insights

Aims To evaluate the relationship of skeletal and respiratory muscular dysf unction with the degree of clinical severity, cardiac impairment and exerci se intolerance in patients with chronic heart failure. Methods and Results Ninety-one patients (age 52.7 +/- 8 years) on standard therapy and in a stable clinical condition with normal nutritional status u nderwent evaluation of (1) clinical severity and metabolic status (NYHA cla ss, weight, albuminaemia, natraemia, cortisol, insulin, neurohormones), (2) cardiac function (Echo, right heart catheterization), (3) exercise toleran ce (peak VO2,), (4) dynamic isokinetic forces of the quadriceps and hamstri ng (Cybex method), and respiratory muscle strength (maximal inspiratory and expiratory pressures). Fifty patients had a peak VO2 <14 ml.kg(-1).min(-1) (10.6 +/- 2) and 41 had values greater than or equal to 14 (18.3 +/- 4). I n the former group, leg and respiratory strength were significantly lower ( extensors: 80 +/- 24 vs 100.9 +/- 22 Nm; flexors: 48.5 +/- 24 vs 75.3 +/- 2 2, both P < 0.001; maximal expiratory pressure: 85.5 +/- 30 vs 104.8 +/- 31 , P < 0.01). Muscular strength was not related to indices of clinical sever ity, metabolic status, neurohormones or to the degree of systolic/diastolic cardiac function, but it was related to weight and age. Multivariate analy sis of the peak VO2 with clinical, haemodynamic and peripheral indicators s howed weight (beta=0.32, P=0.007), muscular strength (beta=0.32, P=0.01) an d NYHA class (beta=0.31, P=0.001) as the only independent predictors. The j oint adjusted R-2 value was 0.48 (P<0.001). Conclusion Muscular dysfunction is part of the syndrome of heart failure. T ogether with symptom perception, it predicts nearly half of the variation i n exercise tolerance.