## **Core Concept**
Classical angina, also known as stable angina, is a condition characterized by chest pain due to transient myocardial ischemia. It is typically triggered by exertion or stress and relieved by rest or nitroglycerin. The management of an acute angina attack focuses on rapidly relieving ischemia and reducing myocardial oxygen demand.

## **Why the Correct Answer is Right**
The correct answer, **C. Nitroglycerin**, is the drug of choice for relieving an acute attack of classical angina. Nitroglycerin works by releasing nitric oxide, which causes vasodilation of blood vessels, particularly the coronary arteries and peripheral veins. This leads to a reduction in myocardial oxygen demand by decreasing preload (the initial stretching of the cardiac myocytes prior to contraction) and possibly increasing coronary blood flow. The rapid onset of action of nitroglycerin makes it ideal for immediate relief during an angina attack.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While beta blockers are a cornerstone in the long-term management of angina by reducing myocardial oxygen demand through decreased heart rate and contractility, they are not used for immediate relief during an acute angina attack due to their slower onset of action.
- **Option B:** Calcium channel blockers can be used in the management of angina, especially in patients who cannot tolerate beta blockers. However, like beta blockers, they are not the first choice for immediate relief of an acute angina attack.
- **Option D:** Aspirin is an antiplatelet agent used in the long-term management of patients with coronary artery disease to prevent myocardial infarction but is not used for the immediate relief of angina symptoms.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is the "ABC" of angina management: **A**spirin for antiplatelet effect, **B**eta-blockers for reducing heart rate and contractility, and **C**oronary vasodilators (like **C**alcium channel blockers or **N**itroglycerin) for immediate relief of symptoms. Specifically, for immediate relief of an angina attack, **N**itroglycerin (or other nitrates) is the go-to medication.

## **Correct Answer:** . Nitroglycerin