Comparative efficacy of the new cardiotonic agent DPI 201-106 versus dobutamine in dilated cardiomyopathy: analysis by serial pressure/volume relations and "on-line" MVO2 assessment.

DPI 201-106 (DPI) as a positive inotropic drug might be useful in treating dilated cardiomyopathy (DCM). In seven DCM patients with normal (group A) and eight DCM patients with abnormal (group B) left ventricular (LV) function, we analyzed serially (computer-assisted) pressure/volume (P/V) effects as P/V loops (microtip catheter/99mTc scintigraphy) using DPI (30 micrograms/kg X min i.v.) and dobutamine (DOB) (10 micrograms/kg X min i.v.) for quantitative comparison of hemodynamic effects. Contractility (dP/dtmax) improvement was greater with DPI (group A, +23%; group B, +47%) than with DOB (group A, +21%; group B, +32%), as was the simultaneous LV end-diastolic pressure decrease--DPI (group A, -39%; group B, -42%) versus DOB (group A, -21%; group B, -18%). LV efficiency increased with DPI (group A, +22%; group B, +55%), but myocardial oxygen consumption (MVO2) did not change significantly. Five of 15 patients showed an increase in dP/dtmax with DPI only; with DPI there were fewer "nonresponders" than with DOB. Thus, DPI increases contractility in DCM hearts while reducing preload rather than causing higher metabolic costs. Such beneficial hemodynamic effects appear to be stronger in the more impaired myocardium (group B patients) and quantitatively superior to those induced by DOB. This might indicate that residual myocardial reserves are more readily accessible to the influences of DPI than to those of DOB. Serial P/V loops and MVO2 assessment aided the demonstration of DPI's efficacy in a more complex way.