Normally the sino-atrial (SA) node is the primary cardiac pacemaker. In MAT, several different irritable atrial cardiac cell clusters have also taken over pacemaker functions. The SA pacer will generally have a normal looking P wave on EKG, with the additional atrial pacers all going off at different rates, and with their own distinct looking P waves. Some may be inverted, others triangularly shaped, etc. The net effect is an irregular atrial tachycardia that could be confused with atrial fibrillation.
Treatment is generally aimed at identifying and treating the underlying cause. ACLS intervention could include slowing down the ventricular response rate. this is typically done with IV Diltiazem, Verapamil, or Beta blockers.