Acute substantial benefit of inotropic therapy with amrinone on exercise hemodynamics and metabolism in severe congestive heart failure

The acute hemodynamic and metabolic effects of amrinone during exercise were studied in eight patients with severe congestive heart failure. The patients exercised to exhaustion on an upright bicycle ergometer at a fixed work load of 25 W. During the control period of exercise, exhaustion occurred at 3.16±1.39 minutes. Stroke volume increased from 29.5±5.8 to 38.7±9.5 ml (p<0.01), arteriovenous oxygen difference from 7.6±1.3 to 9.6±0.6 ml/100 ml (p<0.001), oxygen consumption from 231±38 to 468±111 ml/min (p<0.001) and arterial lactate concentration from 1.07±0.25 to 5.02±1.45 mmol/l (p<0.01). During exercise after administration of amrinone, exhaustion occurred significantly later than during the control period: 6.28±2.07 vs 3.16±1.39 minutes (p<0.05). At a time equal to the point of exhaustion during the control period, stroke volume was significantly greater amrinone (46.7±9.8 vs 38.7±9.5 ml, p<0.05), arteriovenous oxygen difference and arterial lactate concentration were significantly lower (7.7±0.9 vs 9.6±0.6 ml/100 ml [p<0.05] and 2.96±1.01 vs 5.02±1.45 mmol/l [p<0.05], respectively) and oxygen consumption was similar. At the point of exhaustion during exercise after amrinone, there were further increases in stroke volume (to 54.0±11.6 ml, p<0.05), and oxygen consumption (to 674±141 ml/min, p<0.05), while arteriovenous oxygen difference and arterial lactate concentration reached values similar to those during control exercise. Thus, amrinone increased exercise capacity, improved exercise hemodynamics, and probably decreased anaerobic metabolism at a given duration of exercise.