Junctional Escape Rhythm
The patient is an 85-year-old female with paroxysmal atrial fibrillation (AF), hypertension, peripheral vascular disease, hyperlipidemia, and chronic obstructive pulmonary disease who presents to the clinic to follow-up on persistent AF. She is on amiodarone 200 mg PO daily, warfarin 3 mg PO daily, digoxin 125 mcg PO daily, diltiazem 300 mg PO daily, and metoprolol 25 mg PO daily. She endorses fatigue, dyspnea on exertion, dizziness, and nausea. The patient's digoxin level was 1.7 ng/mL. An electrocardiogram (ECG) (Figure 1) is performed and shows the following:
What is the most probable cause of the findings in this ECG?