The emergency ward calls to inform you one of your patients has been admitted to the inpatient medicine service for a GI bleed. The patient is a 79 y/o woman with a history of paroxysmal atrial fibrillation and heart failure with a preserved ejection fraction. Her medications include:  warfarin, sotalol, furosemide, metoprolol, fluoxetine, lisinopril, and vitamin D3. Her INR is found to be 6.4.

The most likely reason for the patient’s elevated INR is:

1. Recent addition of fluoxetine for depression.
2. Recent addition of lisinopril for hypertension.
3. Recent increase in metoprolol dose.
4. Recent addition of Sotalol.