Effects of new inotropic agents on exercise performance.

Area of Science:

• Cardiology
• Pharmacology
• Exercise Physiology

Background:

• Chronic cardiac failure (CCF) limits exercise tolerance due to dyspnea and fatigue.
• Abnormal cardiocirculatory responses to exercise exacerbate CCF symptoms.
• New positive inotropic agents are being investigated for long-term CCF treatment.

Purpose of the Study:

• To evaluate the impact of new positive inotropic agents on exercise performance in CCF patients.
• To assess the potential of these agents to increase aerobic capacity.
• To compare the efficacy of different drug classes, including beta-adrenergic agonists, phosphodiesterase inhibitors, and bipyridine derivatives.

Main Methods:

• Review of clinical experience with positive inotropic agents in CCF.
• Analysis of effects on exercise performance parameters like aerobic capacity and anaerobic threshold.
• Consideration of drug-induced side effects, such as ventricular arrhythmias.

Main Results:

• Beta-adrenergic receptor agonists showed limited benefit and caused arrhythmias.
• Phosphodiesterase inhibitors (MDL 17,043, MDL 19,205) and bipyridine derivatives (amrinone, milrinone) may improve exercise performance.
• These agents demonstrated sustained effects during long-term therapy in some patients.

Conclusions:

• Phosphodiesterase inhibitors and bipyridine derivatives show potential for improving exercise capacity in CCF.
• Further placebo-controlled, randomized trials are essential to establish definitive efficacy and safety.
• Objective exercise parameters are crucial for unbiased assessment of treatment effectiveness.