Multifocal Atrial Tachycardia

Multifocal atrial tachycardia (MAT) is diagnosed by the presence of three or more morphologically distinct P waves and a heart rate between 100/min and 140/min. MAT is caused by multiple areas of increased automaticity or triggered activity within the atria. Underlying pulmonary disease usually triggers MAT. It occurs most often in patients with severe chronic obstructive pulmonary disease (COPD), but it may also occur in patients with pulmonary embolism, congestive heart failure, and hypoxemia. The treatment of these potential precipitating causes is the primary therapy for MAT and minimizing or discontinuing agents that may precipitate MAT (such as β-agonist therapy). If MAT persists despite the appropriate treatment of underlying causes, metoprolol or even high-dose magnesium may improve the tachycardia.