# Situation: A 52-year-old woman with moderate rheumatic mitral stenosis is brought to the emergency room (ER) because of palpitations and shortness of breath that began 6 hours ago. The cardiac monitor shows atrial fibrillation with a ventricular rate of about 150/min. She has no known drug allergies. She is discharged on warfarin with regular international normalized ratio (INR) checks. Which statement shows that she understood the teaching?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=629788  
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> subject: Nursing Practice III — Care of Clients with Problems in Surgery, Oxygenation, Fluid and Electrolytes, Infectious, Inflammatory and Immunologic Response, Cellular Aberrations

## 문제

Situation: A 52-year-old woman with moderate rheumatic mitral stenosis is brought to the emergency room (ER) because of palpitations and shortness of breath that began 6 hours ago. The cardiac monitor shows atrial fibrillation with a ventricular rate of about 150/min. She has no known drug allergies.

She is discharged on warfarin with regular international normalized ratio (INR) checks. Which statement shows that she understood the teaching?

## 보기

1. "Later I can switch to a newer blood thinner that needs no blood tests."
2. "I will eat about the same amount of green leafy vegetables each week." **✔ 정답**
3. "I can stop the warfarin once my palpitations have gone away."
4. "I will take mefenamic acid for my menstrual cramps as I did before."

**정답: 2**

## 해설

Warfarin acts against vitamin K, so a steady intake of vitamin K–rich green leafy vegetables keeps the INR stable. Direct oral anticoagulants are not used for atrial fibrillation with moderate to severe rheumatic mitral stenosis, NSAIDs such as mefenamic acid add to bleeding risk, and anticoagulation continues even when she feels well.

## 심화 해설

Consistent vitamin K keeps the INR stable
Warfarin is a vitamin K antagonist: it blocks the liver's recycling of vitamin K, which is needed to activate clotting factors II, VII, IX, and X. Because its effect depends on how much vitamin K is available, sudden changes in the intake of vitamin K-rich foods such as green leafy vegetables change the international normalized ratio (INR). The safest teaching is not to avoid these foods but to eat about the same amount each week, so that the warfarin dose can be matched to a stable diet. Her statement shows she understood this.

Why warfarin, not a newer anticoagulant
She has atrial fibrillation with moderate rheumatic mitral stenosis. In this group, the stroke risk is high and direct oral anticoagulants are not used; warfarin with regular INR monitoring is the standard. Her plan to switch later to a newer drug that needs no blood tests is therefore incorrect and shows a gap in understanding. Anticoagulation is also long term: stopping warfarin when the palpitations settle leaves the atria prone to clot, because the rhythm and the valve disease, not the symptom, determine the risk.

| Statement | Assessment | Reason |
| --- | --- | --- |
| Same amount of green leafy vegetables each week | Correct | Stable vitamin K keeps the INR stable |
| Switch later to a newer drug without blood tests | Incorrect | DOACs are not used with moderate to severe rheumatic mitral stenosis |
| Stop warfarin when palpitations go away | Incorrect | Stroke risk persists; therapy is long term |
| Mefenamic acid for menstrual cramps | Incorrect | NSAIDs add to bleeding risk |

Drug interactions and bleeding risk
Mefenamic acid is a nonsteroidal anti-inflammatory drug. NSAIDs impair platelet function and irritate the stomach lining, so combined with warfarin they raise the risk of gastrointestinal and other bleeding. Paracetamol (acetaminophen) is the preferred analgesic for menstrual cramps unless her provider advises otherwise. Other teaching includes reporting bleeding signs such as dark stools, blood in the urine, heavy menstrual flow, or easy bruising, telling every provider and dentist that she takes warfarin, and keeping her scheduled INR checks.

Watch out! A common distractor tells clients to stop eating green vegetables. This is unnecessary and can make the INR unstable when the food is eaten again. Consistency, not avoidance, is the rule.

Exam takeaway
Key point! For warfarin teaching, look for consistent vitamin K intake, regular INR checks, avoidance of NSAIDs and unadvised supplements, and long-term use. In atrial fibrillation with moderate to severe rheumatic mitral stenosis, warfarin is required and DOACs are not substituted.

## 임상 시나리오

Warfarin TeachingAtrial fibrillation with rheumatic mitral stenosis
Warfarin works against vitamin K. Eating about the same amount of green leafy vegetables each week keeps the INR stable; avoidance is not required.

With moderate to severe rheumatic mitral stenosis, direct oral anticoagulants are not used. Warfarin with regular INR checks is continued long term, even when palpitations settle.

Use paracetamol rather than NSAIDs such as mefenamic acid, report signs of bleeding, and tell every provider and dentist about warfarin.

CautionStopping warfarin when she feels well leaves her at high risk of stroke from atrial clots.

## 핵심 개념

- **Warfarin** — An oral anticoagulant that blocks vitamin K-dependent clotting factors and is monitored with the INR.
- **International normalized ratio** — A standardized measure of prothrombin time used to adjust the warfarin dose.
- **Rheumatic mitral stenosis** — Narrowing of the mitral valve after rheumatic fever, which raises the risk of atrial clots in atrial fibrillation.
- **Direct oral anticoagulant** — A newer oral anticoagulant that needs no routine INR checks but is not used with significant rheumatic mitral stenosis.
- **NSAID** — A nonsteroidal anti-inflammatory drug that impairs platelets and raises bleeding risk when combined with warfarin.

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