What do the newer inotropic drugs have to offer?

Intensive interest and passion have been generated in the search for orally effective inotropes over the past few decades. Several extensive clinical evaluations of these agents have now been completed. Both beta-adrenergic agonists and phosphodiesterase inhibitors that exert cardiotonic action by increasing intracellular cyclic adenosine monophosphate produced dramatic short-term hemodynamic benefits in patients with advanced heart failure. However, patients who received long-term treatment with these agents had unfavorable outcomes, including a higher mortality and morbidity rate, and deleterious side effects. The principal mechanisms responsible for the limitations in its usefulness in long-term therapy may be related to increased energy expenditure and potential arrhythmogenic effects. In contrast to these pessimistic views, one quinolinone derivative has been shown to exert a positive inotropic action without a chronotropic effect. Patients with mild heart failure responded favorably to this agent in long-term therapy. The lack of an increase in heart rate might be the cause of this salutary effect. Concerns regarding the possible improvement in the prognosis of patients with heart failure due to the use of positive inotropic therapy still continue.