Preservation of exercise capacity and lack of peripheral changes in asymptomatic patients with severely impaired left ventricular function

Aims: To establish the extent, if any, of peripheral changes in asymptomatic patients with severe left ventricular dysfunction.

Methods and Results: Nine asymptomatic and nine symptomatic patients with left ventricular ejection fraction, <25%, matched for age and left ventricular ejection fraction (asymptomatic vs symptomatic, age: 52±1·5 vs 55·9±2·5 years [Mean±SEM], left ventricular ejection fraction: 16±2 vs 19±2%P=0·23 and 0·48, respectively) were studied and compared with 26 age-matched normal controls. We assessed exercise capacity, leg blood flow (occlusion plethysmography), respiratory muscle strength, quadriceps maximal isometric strength, fatigue and CT cross-sectional muscle area at mid thigh. Fatigue was expressed as the percentage reduction in maximal strength following a 20min fatiguing protocol. There was a graded increase in peak oxygen consumption comparing symptomatic, asymptomatic and control groups (16·6±1·3 vs 27·1±1·6 vs 32·8±1·3ml.min−1.kg−1respectively, ANOVA P<0·0001). Between the three groups there was significant variation in muscle strength (P<0·0001), endurance (P=0·0002) and cross-sectional area (P=0·0003) and in peak blood flow (P=0·027) and respiratory muscle strength (P<0·05). When asymptomatic patients and controls were compared no significant differences existed.

Conclusions: Patients with severe left ventricular dysfunction may have near normal exercise capacity and no peripheral changes. Exercise capacity may depend less upon left ventricular function than on the presence or absence of peripheral factors.