Citation: Negrete AM. Heart of the Matter - Irregularly Irregular, but Not Atrial Fibrillation?[Internet]. Cook County Emergency Medicine Residency;Available from: https://cookcountyem.com/blog/2023/8/21/the-heart-of-the-matter-irregularly-irregular-but-not-a-fib
A 68-year-old male with a PMHx of PE on apixaban, HTN presents with fatigue and several days of diarrhea.
Rate?
Rhythm?
Axis?
Intervals?
QRST?
Interpretation: Irregularly irregular tachycardia, Rate 170 beats/min, borderline LAD, normal QRS, varying P-P, P-R, QRS-QRS intervals.
Discussion: This is an SVT and the differential includes atrial fibrillation, atrial flutter with variable block, and MAT. In this case, given the atrial rate was sustained but the patient was stable (otherwise the answer is electricity), we attempted 6mg of IV adenosine to help identify the rhythm.
This helped show the patient was in Multifocal Atrial Tachycardia due to severe hypomagnesemia and hypokalemia in the setting of new onset C. difficile infection.
Take away points:
Always consider MAT in any irregularly irregular rhythm. Remember MAT can be due to hypok/hypomag and not just pulmonary disease. Treat the underlying cause which in this case was a goal K>4 mEq/L and Mg >2 mEq/L. Medical therapy for MAT is indicated only if MAT causes a sustained rapid ventricular response that causes or worsens myocardial ischemia, heart failure, peripheral perfusion, or oxygenation. In this case, you may consider verapamil or beta-blockers (be cautious of beta-blocker use in decompensated HF or obstructive pulmonary disease!).
Authored by Alejandro Negrete, MD
References:
Buxton A. Multifocal atrial tachycardia [Internet]. UpToDate. [cited 2023 Aug 16];Available from: https://www.uptodate.com/contents/multifocal-atrial-tachycardia?search=mat&source=search_result&selectedTitle=1~25&usage_type=default&display_rank=1#H754574
Multifocal atrial tachycardia [Internet]. WikEM. [cited 2023 Aug 16];Available from: https://wikem.org/wiki/Multifocal_atrial_tachycardia
Custer AM, Yelamanchili VS, Lappin SL. Multifocal Atrial Tachycardia. [Updated 2022 Jul 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459152/
Burns E and Buttner R. Multifocal Atrial Tachycardia (MAT) [Internet]. Life in the Fast Lane • LITFL. 2021 [cited 2023 Aug 16];Available from: https://litfl.com/multifocal-atrial-tachycardia-mat-ecg-library/