Case Files 11: My Heart Skipped A Beat - SOLVED

A 68 years old lady presented to the ED with productive cough for the past 3 days. She was brought today in view of her complains of generalized lethargy and weakness. Prior to further investigations, a baseline ECG was done. She was initially sent for green zone fast track, but was subsequently uptriage to yellow. What are your findings?

This is a rare pattern of atrial bigeminy. While most are familiar with the easy-to-spot ventricular bigeminy with a wide QRS complex, this can be rather confusing as one may thought of Mobitz type II or 2:1 block. However, a closer look will reveal a few things:
1) The QRS complex exhibits grouped beating, being regularly irregular
2) There are presence of P waves prior to each QRS complexes
3) All P wave have an associated QRS complexes
4) The 2nd P wave have slightly different morphology than the 1st P wave, suggestive of 1st P wave originated from the sinus focus whilst the 2nd P (premature atrial contraction) may originate from another focus.

Atrial bigeminy, as a manifestation of premature atrial contraction, is a harmless rhythm in the proper clinical context. Most people with atrial bigeminy do not have organic heart disease, albeit the fact that it is more common in people with heart disease than those without. There are certain factors linked to the occurence of atrial bigeminy, such as caffein intake, emotional stress, smoking, alcohol use and fatigue. One things is of concern is that patioent with atrial bigeminy may not have the 2nd QRS wave transmitted into a pulse, which had caused this patient to have a pulse rate of 50-60 despite a heart rate of 100-110.

In this patient, no identifiable cause was found despite the alert and uptriage to Red Zone initially. Repeated ECG 1 hour later showed resolution to sinus rhythm and her pulse rate returned to 80-90 beats per minute. Nevertheless, the patient was admitted for community acquired pneumonia with a high CURB-65 score.

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