What is the treatment for multifocal atrial tachycardia (MAT)?

From the Guidelines

The primary approach to treating multifocal atrial tachycardia (MAT) should focus on managing the underlying condition, with intravenous magnesium and calcium channel blockers like verapamil being considered for acute treatment, as recommended by the 2015 ACC/AHA/HRS guideline 1.

Key Considerations

• MAT is often associated with underlying conditions such as pulmonary disease, pulmonary hypertension, coronary disease, and valvular heart disease, as well as hypomagnesemia and theophylline therapy 1.
• The first-line treatment is management of the underlying condition, which may involve treating respiratory infections, correcting electrolyte abnormalities, optimizing oxygenation, and discontinuing proarrhythmic medications.
• Intravenous magnesium may be helpful in patients with normal magnesium levels, and calcium channel blockers like verapamil can be useful for acute treatment in patients with MAT, as they can terminate the arrhythmia or slow the ventricular response 1.

Treatment Options

• Intravenous metoprolol or verapamil can be useful for acute treatment in patients with MAT, with the choice depending on the patient's underlying condition and the presence of any contraindications, such as severe pulmonary disease or acute decompensated heart failure 1.
• Magnesium supplementation (2 g IV over 15 minutes, followed by continuous infusion) can be beneficial even in patients with normal magnesium levels.
• Antiarrhythmic drugs like amiodarone may be considered in refractory cases, but their use should be cautious due to potential side effects.

Important Considerations

• Electrical cardioversion is generally ineffective for MAT due to its automatic mechanism and multiple foci.
• MAT is challenging to treat because it arises from multiple ectopic atrial pacemakers with varying automaticity, often in the setting of significant cardiopulmonary disease, making management of the underlying condition crucial for successful control of the arrhythmia.

From the Research

Treatment of Multifocal Atrial Tachycardia

The treatment of multifocal atrial tachycardia (MAT) should first be directed at potential predisposing factors, such as:

• Hypoxia
• Congestive heart failure
• Theophylline toxicity 2 It is also recommended to include supportive measures and aggressive reversal of precipitating causes 3

Pharmacologic Treatment

Pharmacologic treatment of MAT includes:

• Intravenous metoprolol
• Verapamil, both of which have been well tolerated and have controlled the heart rate in a majority of patients 2 Other agents that may have a role in the treatment of MAT are:
• Magnesium 3

Mechanism and Clinical Correlates

The mechanism of MAT is thought to be triggered activity arising from increased intracellular calcium stores, which may be produced by:

• Hypokalemia
• Hypoxia
• Acidemia
• Increased catecholamines 4 MAT is commonly seen in elderly patients with severe illnesses, most commonly COPD, and its importance lies in the fact that it is commonly mistaken for atrial fibrillation (AF) 4

Clinical Settings and Prognosis

MAT is often found in patients with:

• COPD
• Coronary artery disease
• CHF
• Infection (both pulmonary and nonpulmonary) 4 Mortality is very high in all patients studied, ranging from 38% to 62%, and is due to their underlying disease processes and not to the arrhythmia 4