MYOCARDIAL ENERGETICS AND EFFICIENCY IN PATIENTS WITH IDIOPATHIC CARDIOMYOPATHY - RESPONSE TO DOBUTAMINE AND AMRINONE

Nine consecutive patients having severer idiopathic dilated cardiomyopathy were studied for their response in ventricular function, coronary sinus blood flow and myocardial oxygen consumption, lactate extraction and efficiency following incremental doses of dobutamine, followed by the combination of dobutamine and the phosphodiesterase inhibitor amrinone. Results, presented as baseline and the response to the peak dose (15μg/kg/min) of dobutamine and to the combination of dobutamine and amrinone (each at 15 μg/kg/min) (differences compared with baseline) were: wedge pressure decreased from 28±7 to 26±8 mm Hg (p=NS) and to 20±6 mm Hg (p<0.01); cardiac index rose from 1.47±0.44 L/min/m2 to 2.80±1.1 L/min/m2 (p<0.01) and to 3.64±1.05 L/min/m2 (p<0.001); myocardial oxygen consumption minute work fror (18±8, 17±5, and 19±5 ml/min) despite progressive increments in (p<0.001); myocardial lactate extraction rose from 21±10% to 30±15% (p=NS) and to 35±10% with the addition of amrinone (p<0.01). No patient had net lactate efflux into the coronary sinus, and myocardial efficiency improved from 9.5±5% to 21.7±13.0% (p<0.01) and to 28.0±18.0% (p<0.01). Thus in idiopathic dilated cardiomyopathy, dobutamine and the combination of dobutamine and amrinone have additive beneficial effects on ventricular performance without an adverse elevation in myocardial oxygen consumption or lactate production, resulting in improved efficiency, suggesting the presence of significant metabolic reserve within the failing myocardium. © 1990 Mosby-Year Book, Inc.