Situation: A 70-year-old woman with rheumatic heart disease is in the coronary care unit. An echocardiogram shows moderate mitral stenosis. She has had palpitations for about 4 days, and the monitor shows atrial fibrillation (AF) with a ventricular rate of 150–160/min. She has not been taking an anticoagulant. The next day she is hemodynamically stable with bibasilar crackles. Her kidney function is normal, and she has no chronic lung disease. The physician writes these orders. Which order should the nurse clarify before carrying it out?

Direct oral anticoagulants such as apixaban are preferred for most clients with AF, but not for those with moderate to severe mitral stenosis, who need warfarin with international normalized ratio monitoring. Beta blockers are helpful in mitral stenosis because a slower rate lengthens diastolic filling.

Why apixaban must be clarified

Moderate mitral stenosis changes the anticoagulation decision entirely. In most clients with atrial fibrillation, a direct oral anticoagulant (DOAC) such as apixaban is the preferred choice because it reduces stroke and systemic embolism by at least two thirds and mortality by about one fourth compared with no anticoagulation ^[1]. However, the safety and efficacy of DOACs have not been established in clients with moderate to severe mitral stenosis, particularly when the stenosis is rheumatic in origin ^[2][3]. These clients were largely excluded from the landmark DOAC trials, so the evidence base for apixaban in this specific population is insufficient ^[3]. For hemodynamically stable clients with atrial fibrillation and moderate to severe mitral stenosis, the anticoagulant that remains appropriate is warfarin with international normalized ratio (INR) monitoring, not a DOAC ^[2][4].

Why the other orders are appropriate

Metoprolol is a beta blocker that slows the ventricular rate. In mitral stenosis, the left atrium cannot empty efficiently into the left ventricle because the valve opening is narrowed. When the ventricular rate is very high, as seen here at 150–160/min, diastole becomes dangerously short. Diastole is the only time blood can flow across the stenotic mitral valve into the left ventricle. A slower heart rate lengthens diastolic filling time, which lowers left atrial pressure and improves forward flow ^[4]. Beta blockers are therefore a core part of rate control in mitral stenosis with atrial fibrillation ^[4].

Furosemide is a loop diuretic. The bibasilar crackles indicate pulmonary congestion from elevated left atrial and pulmonary venous pressure. Reducing intravascular volume with intravenous furosemide relieves that congestion. Diuretics are part of symptom management in rheumatic heart disease when congestion is present ^[4].

Oxygen by nasal cannula to maintain saturation at 94–98% is a supportive measure for a client with crackles and possible hypoxemia. There is no contraindication here; the client has no chronic lung disease, so targeting this saturation range is safe and appropriate.

Clinical reasoning for the licensure exam

The key discriminator in this question is not whether anticoagulation is needed. It is which anticoagulant is correct. Watch out! DOACs are first-line for most atrial fibrillation, but moderate to severe mitral stenosis is a major exception. Key point! Rheumatic mitral stenosis with atrial fibrillation requires warfarin, not apixaban, because DOAC trials did not include these clients and the thrombotic mechanism differs.

Order	Rationale	Action
Oral metoprolol	Slows ventricular rate; lengthens diastolic filling across stenotic mitral valve [4]	Carry out
Oral apixaban	DOAC efficacy and safety not established in moderate to severe mitral stenosis [2][3]	Clarify; warfarin with INR monitoring is indicated [2][4]
IV furosemide	Reduces pulmonary congestion from elevated left atrial pressure [4]	Carry out
Oxygen via nasal cannula	Supports oxygenation with target saturation 94–98%	Carry out

The order that must be clarified before administration is oral apixaban, because it is contraindicated or at least unsupported for stroke prevention in this client with moderate rheumatic mitral stenosis and atrial fibrillation.