What is the management for a patient with Heart Failure with Reduced Ejection Fraction (HFrEF) of 20%, atrial fibrillation (AF) with rapid ventricular response, on milrinone at 0.125 micrograms/minute, and tacrolimus and azithromycin, who has shown mild improvement with amiodarone infusion, but now presents with prolonged QT/QTc interval at 366/488 milliseconds?

From the Guidelines

Discontinuing amiodarone is crucial in this patient with heart failure with reduced ejection fraction (HFrEF) and atrial fibrillation (AF) due to the prolonged QTc interval of 488 ms, which poses a significant risk of torsades de pointes, especially with concomitant use of azithromycin and tacrolimus 1. The patient's current medication regimen, including amiodarone, azithromycin, and tacrolimus, increases the risk of QT prolongation, making it essential to adjust the medications to prevent potentially life-threatening arrhythmias. For rate control, consider using a beta-blocker like metoprolol or a calcium channel blocker like diltiazem, titrated carefully given the reduced ejection fraction, as recommended for patients with HFrEF and AF 1. Some key points to consider in managing this patient include:

• Monitoring the QT interval closely, as it may normalize after discontinuing amiodarone and azithromycin (if clinically appropriate) 1.
• Continuing milrinone for inotropic support but watching for potential arrhythmias, as it is crucial for maintaining cardiac function in patients with HFrEF 1.
• Considering electrical cardioversion as a safer alternative to antiarrhythmic medications if rhythm control remains necessary, especially given the patient's prolonged QTc interval and the risks associated with antiarrhythmic drugs 1.
• Checking electrolytes (particularly potassium and magnesium) and correcting any abnormalities to reduce arrhythmia risk, as electrolyte imbalances can contribute to QT prolongation and arrhythmias 1. Given the complexity of this patient's condition, with HFrEF, AF, and a prolonged QTc interval, a comprehensive approach that prioritizes both rate control and the prevention of arrhythmias is necessary, taking into account the potential benefits and risks of each treatment strategy 1.

From the FDA Drug Label

Proarrhythmia, primarily torsade de pointes (TdP), has been associated with prolongation by amiodarone HCl injection of the QTc interval to 500 ms or greater. Although QTc prolongation occurred frequently in patients receiving amiodarone HCl injection, torsade de pointes or new-onset VF occurred infrequently (less than 2%) Patients should be monitored for QTc prolongation during infusion with amiodarone HCl injection. Combination of amiodarone with other antiarrhythmic therapy that prolongs the QTc should be reserved for patients with life-threatening ventricular arrhythmias who are incompletely responsive to a single agent. Fluoroquinolones, macrolide antibiotics, and azoles are known to cause QTc prolongation There have been reports of QTc prolongation, with or without TdP, in patients taking amiodarone when fluoroquinolones, macrolide antibiotics, or azoles were administered concomitantly

The patient has a QTc interval of 488 ms, which is greater than 500 ms is not met but close, and is taking azithromycin, a macrolide antibiotic known to cause QTc prolongation.

• The patient should be closely monitored for QTc prolongation and torsade de pointes.
• Consider reducing the rate of administration or withdrawing amiodarone due to the potential risk of proarrhythmia.
• Alternative treatments should be considered due to the patient's high risk of QTc prolongation 2.

From the Research

Patient Assessment

• The patient has heart failure with reduced ejection fraction (HFrEF) at 20% and atrial fibrillation (AF) with rapid response.
• The patient is taking milrinone at 0.125 mcg/min, tacrolimus, and azithromycin.
• An EKG shows QT/QTc at 366/488, indicating QT prolongation.

Risk Factors for QT Prolongation

• The patient is taking multiple medications that can prolong the QT interval, including azithromycin and amiodarone 3, 4.
• The patient has heart failure, which is a risk factor for QT prolongation 5.
• The patient's QTc interval is prolonged at 488 ms, which increases the risk of torsades de pointes (TdP) 6, 5.

Management

• Close monitoring of the patient's EKG and electrolytes is necessary to prevent TdP 5.
• Consider discontinuing or reducing the dose of medications that can prolong the QT interval, such as azithromycin and amiodarone, if possible 5.
• Correct any electrolyte imbalances, such as hypokalemia or hypomagnesemia, which can contribute to QT prolongation 5.
• Consider alternative antiarrhythmic medications that do not prolong the QT interval 7.

Considerations

• The combination of azithromycin and amiodarone can increase the risk of QT prolongation and TdP 3, 4.
• Elderly women with heart disease, like this patient, may be at particularly high risk for drug-related QTc interval prolongation and TdP 4.
• The patient's QTc interval is not severely prolonged, but close monitoring is still necessary to prevent TdP 6, 5.