What is MAT ( Multifocal Atrial Tachycardia) ?

Shine, Kastor and Yurchak first proposed this definition of MAT in 1968. MAT result from an extremely rapid firing of multifocal ectopic sites . very rare in healthy individuals , this arrhythmia is usually found in acutely ill patients with pulmonary disease or elevated atrial pressure . Its rapid and irregular cardiac rhythm originating from two or more different portions of the atrial . MAT has previously been described by terms such as chaotic atrial rhythm or tachycardia, chaotic atrial mechanism, and repetitive paroxysmal MAT.

 

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Diagnostic characteristics
1- two or more ectopic P waves with different configurations and two or more different ectopic P-O cycles .

2- Atrial rate of 100-250 bpm ( occasionally <100bpm)

3- isoelectrical line present between P-P interval .

4- Frequent occurrence of varying P-R intervals and AV block of varying degree ( non-  conducted ectopic P waves ) .

because of the irregular ventricular cycles in MAT , AF is superficially simulated . The presence of P waves with various configuration excludes the possibility of AF . MAT is most commonly encountered in patient with COPD .

The evidence that implicates this mechanism is mainly indirect and points to intracellular calcium overload by various mechanisms (eg, catecholamine excess, phosphodiesterase inhibition, acidosis, hypoxemia). Electrolyte imbalances associated with severe underlying illnesses can further potentiate the development of this arrhythmia. MAT most often is found in the elderly patient with decompensated chronic lung disease and should be thought of as a hypoxic complication of underlying heart conduction pathology. However, other underlying causes may be present, such as heart failure, sepsis, or methylxanthine toxicity.

–         Usually , complaint as a palpitation

–         Rapid apical or peripheral pulse rate

–         Signs and symptoms of decreased cardiac output , such as hypotension , syncope , blurred vision .