A 60-year-old male patient is receiving aspirin, atorvastatin, isosorbide mononitrate, and a beta-blocker for chronic stable angina. He presents to the ER with episodes of unusually severe and long-lasting anginal chest pain each day over the past 3 days. His ECG and cardiac enzymes are normal. Which of the following is the best course of action?

**Core Concept**
The patient's presentation of severe and long-lasting anginal chest pain despite receiving standard therapy for chronic stable angina suggests a need for a change in management strategy. This may be due to a phenomenon known as **Prinzmetal's angina**, also known as variant angina, which is caused by transient coronary artery spasm.

**Why the Correct Answer is Right**
In this scenario, the patient's symptoms are likely due to coronary artery spasm, which is not responsive to the standard therapy for chronic stable angina. The best course of action is to add a medication that can help to prevent or relieve coronary artery spasm. **Nitrates** are a class of medications that can help to relax the smooth muscle of the coronary arteries and prevent spasm. In this case, adding a long-acting nitrate such as **isosorbide dinitrate** to the patient's regimen would be the best course of action.

**Why Each Wrong Option is Incorrect**
**Option A:** Adding a beta-blocker would be counterproductive, as beta-blockers can actually worsen coronary artery spasm by causing vasoconstriction.

**Option B:** Switching to a different beta-blocker would not address the underlying issue of coronary artery spasm.

**Option C:** Adding a calcium channel blocker, while potentially beneficial, is not the most effective initial approach in this scenario.

**Clinical Pearl / High-Yield Fact**
When managing patients with angina, it's essential to consider the possibility of variant angina, especially if the patient's symptoms are not responsive to standard therapy.

**Correct Answer:** C.

✓ Correct Answer: B. Admit the patient and begin low-molecular-weight (LMW) heparin and clopidogrel