Effects of a new cardiotonic agent, "TA-064", in patients with dilated cardiomyopathy : Relationship between cardiac effect of TA-064 and severity of myocardial lesion.

In 18 patients with dilated cardiomyopathy (DCM), the effects of a new cardiotonic agent, TA-064, given in both consecutive and intermittent (3 days on, 11 days off) oral doses were studied for 3 months by echocardiography and endomyocardial biopsy. After 3 months of consecutive administration, 11 patients (61%) had improved symptomatically and the %FS increased (p less than 0.001) and LVDd decreased (p less than 0.05), but the other 7 patients had not improved. At the pretreatment state these 7 patients in whom TA-064 was not effective had smaller %FS (p less than 0.01) and larger LVDd (p less than 0.05) than the 11 patients in whom the drug was effective. The non-effective group also had more severe myocardial fibrosis (p less than 0.05) and cellular hypertrophy (p less than 0.01) than the effective group. After 3 months of intermittent administration in 10 patients in whom consecutive administration had been proved effective, 7 patients sustained symptomatic improvement and increased %FS (p less than 0.01), but the other 3 patients did not sustain the improvement. The latter group had smaller %FS, larger LVDd and more severe myocardial fibrosis than the former group at the pretreatment state. These results indicate that the effects of TA-064 are dependent on the severity of basal cardiac function and myocardial damage, and that in patients with milder DCM, the effects can be sustained by intermittent administration.