What is an inotropic (inotrope) agent?

From the Guidelines

An inotrope is a medication that increases the force of heart muscle contractions, commonly used to treat conditions like heart failure and cardiogenic shock. According to the 2022 AHA/ACC/HFSA guideline for the management of heart failure 1, intravenous inotropic support can increase cardiac output and improve hemodynamics in patients presenting with cardiogenic shock.

Key Characteristics of Inotropes

• Positive inotropes, such as digoxin, dobutamine, milrinone, epinephrine, and norepinephrine, increase the strength of heart contractions.
• These medications work through different mechanisms, including increasing calcium availability in heart cells or stimulating beta-adrenergic receptors.
• Inotropes are typically administered intravenously in hospital settings, especially in intensive care units, where patients can be closely monitored for potential side effects.

Administration and Monitoring

• The choice of a specific inotropic agent is guided by blood pressure, concurrent arrhythmias, and availability of the drug 1.
• The dosing of inotropes varies by medication and patient condition, and they are often titrated based on response.
• Close monitoring is necessary due to potential side effects such as arrhythmias, tachycardia, or changes in blood pressure.

Clinical Context

• Inotropes are used as part of a broader strategy for managing cardiogenic shock, which may include vasopressors, mechanical circulatory support, and team-based management 1.
• The use of inotropes should be considered in the context of the patient's overall prognosis, wishes, and assessment of therapeutic risk.

From the FDA Drug Label

Dobutamine is a direct-acting inotropic agent whose primary activity results from stimulation of the β receptors of the heart Inotropic support in the short-term treatment of patients with cardiac decompensation due to depressed contractility An inotrope is a medication that increases the contractility of the heart.

• Key characteristics: increases cardiac output, stimulates β receptors of the heart, and is used for short-term treatment of cardiac decompensation due to depressed contractility 2, 2.

From the Research

Definition and Purpose of Inotropes

• Inotropes are medications used to increase the contractility of the heart, often utilized in the treatment of acute decompensated heart failure and cardiogenic shock 3, 4.
• They are designed to enhance the heart's pumping ability, thereby improving cardiac output and overall circulation 4.

Types of Inotropes

• Commonly used inotropes include dobutamine, milrinone, dopamine, norepinephrine, epinephrine, and levosimendan 3.
• Each inotrope has its own mechanism of action, indications, and contraindications, which are crucial for effective and safe utilization in clinical settings 3, 4.

Clinical Utility and Comparison

• Studies have compared the effectiveness and safety of different inotropes, such as milrinone and dobutamine, in the management of cardiogenic shock and acute decompensated heart failure 5, 6.
• The choice between these inotropes may depend on their adverse event profiles, with milrinone and dobutamine demonstrating similar effectiveness but differing in terms of arrhythmias and hypotension 5, 6.

Use in End-Stage Heart Failure

• Inotropes, such as milrinone or dobutamine, are also used in the palliative care of patients with end-stage heart failure, raising questions about their role in hospice care and the criteria for determining ongoing clinical benefit 7.