Multifocal Atrial Tachycardia (MAT)

Frank G. Yanowitz, M.D. Copyright 1998

The features of MAT are best seen in the long V1 rhythm strip. P waves of at least 3 different morphologies are present. The ventricular rate is "irregularly irregular" with the main differential diagnosis being atrial fibrillation. In many of the leads, this ECG looks just like atrial fib. Also present are marked left axis deviation, probably due to left anterior fascicular block, and diffuse ST-T wave abnormalities.