Positive Inotropic Therapy for Chronic Heart Failure: New Perspective on Therapeutic Strategies

Abstract

Despite enthusiasm for the clinical benefits of converting enzyme inhibitors, many patients fail to respond to this therapy. Although positive inotropic therapy can lead to symptomatic relief, a pressing therapeutic goal at the late stage of congestive heart failure, numerous attempts to utilize cyclic AMP-enhancing positive inotropic agents to increase life expectancy have been disappointing. Recently, however, promising results were introduced with digitalis glycoside and agents with mixed mechanisms of inotropic actions. These experiences have led to the concept that to be clinically beneficial and well tolerated, positive inotropic agents should enhance myocardial contractility to only a modest degree without activating the sympathetic and renin-angiotensin systems. In terms of the prognostic benefit from positive inotropic therapy, a little hemodynamic improvement seems to go a long way. Therefore consideration of the mechanism of inotropic action, selection of the proper drug dose, and the influence on autonomic balance may ultimately make critical contributions to the long-term clinical effects of positive inotropic agents.