What is the inotrope of choice in patients prone to tachyarrhythmias?

From the Guidelines

Levosimendan is the inotrope of choice in patients prone to tachyarrhythmias. Unlike traditional inotropes such as dobutamine or milrinone that increase intracellular calcium and can trigger arrhythmias, levosimendan works by sensitizing cardiac troponin C to calcium, improving contractility without significantly raising intracellular calcium levels 1. The typical dosing is a loading dose of 6-12 mcg/kg over 10 minutes followed by a continuous infusion of 0.05-0.2 mcg/kg/min for 24 hours.

When using levosimendan, monitor for hypotension as it has vasodilatory effects, and ensure adequate volume status before initiation. Key benefits of levosimendan include:

• Improved symptoms in acute heart failure
• Reduced mortality in the first 72 hours and up to 6 months after myocardial infarction 1
• Lower risk of triggering arrhythmias compared to traditional inotropes

If levosimendan is unavailable, alternative options may be considered, but they should be chosen with caution due to their potential to exacerbate tachyarrhythmias. The choice of inotrope should always prioritize minimizing the risk of arrhythmias while providing necessary hemodynamic support.

From the FDA Drug Label

Milrinone lactate is a positive inotrope and vasodilator, with little chronotropic activity different in structure and mode of action from either the digitalis glycosides or catecholamines Milrinone lactate, at relevant inotropic and vasorelaxant concentrations, is a selective inhibitor of peak III cAMP phosphodiesterase isozyme in cardiac and vascular muscle This inhibitory action is consistent with cAMP mediated increases in intracellular ionized calcium and contractile force in cardiac muscle, as well as with cAMP dependent contractile protein phosphorylation and relaxation in vascular muscle Additional experimental evidence also indicates that milrinone lactate is not a beta-adrenergic agonist nor does it inhibit sodium-potassium adenosine triphosphatase activity as do the digitalis glycosides

Milrinone may be considered the inotrope of choice in patients who are prone to Tachyarrhythmia because it has little chronotropic activity, meaning it does not significantly increase heart rate, reducing the risk of tachyarrhythmias 2.

• Key benefits of milrinone include its ability to increase myocardial contractility and improve diastolic function without significantly affecting heart rate.
• Main advantages of milrinone over other inotropes, such as catecholamines, include its selective inhibition of phosphodiesterase and lack of beta-adrenergic agonist activity.

From the Research

Inotrope of Choice in Patients Prone to Tachyarrhythmia

• The choice of inotrope in patients prone to tachyarrhythmia is crucial, as some inotropes can exacerbate this condition 3.
• Milrinone has been shown to be a good alternative when inotropes are required in Takotsubo cardiomyopathy and when dobutamine infusion is associated with tachyarrhythmia 4.
• Levosimendan has been found to be equally effective as dobutamine in increasing and maintaining adequate cardiac index, and it does not increase heart rate, making it a potential option for patients prone to tachyarrhythmia 5, 6.
• However, levosimendan has been associated with ventricular tachyarrhythmia as an adverse event, which should be considered when selecting an inotrope 7.
• The choice of inotrope should be individualized based on the patient's specific condition and response to treatment, and careful monitoring of heart rate and rhythm is essential to minimize the risk of tachyarrhythmia 3, 4, 5, 6, 7.

Comparison of Inotropes

• Levosimendan and milrinone have been compared in various studies, with levosimendan showing better hemodynamic favorability in patients undergoing cardiac surgery 6.
• Dobutamine has been associated with increased heart rate and may not be the best option for patients prone to tachyarrhythmia 4, 5.
• The selection of an inotrope should be based on the patient's underlying condition, the presence of tachyarrhythmia, and the potential risks and benefits of each inotrope 3, 4, 5, 6, 7.