Irregularly irregular narrow complex at 115/minute – ? rhythm
Axis – normal
Intervals – there is a P wave in many R-R spaces, of varying PR
No chamber enlargement, ischemia or infarct patterns
There are two irregularly irregular rhythms – atrial fibrillation and multifocal atrial tachycardia (MAT). MAT is defined as >3 ectopic atrial foci with P waves of differing P wave morphology and differing PR intervals. The R-R intervals are necessarily irregularly irregular. In many of the R-R intervals in this lead II rhythm strip, notice that the T wave is “deformed” by the addition of a P wave.
MAT is often seen in COPD, especially during exacerbation. Other causes are any critical illness, especially with depletion of electrolytes and cations. There is no specific treatment of MAT – first, remedy any underlying process like hypoxia, exacerbation of COPD, fluid status.
And remember this sneaky rhythm when atrial fibrillation with very rapid ventricular rate doesn’t respond to usual treatment for a fib – it may be misdiagnosed multifocal atrial tachycardia (MAT)!