Agent of first choice in an acute attack of Prinzmetal’s angina is –
**Core Concept**
Prinzmetal's angina, also known as variant angina, is a condition characterized by transient, recurrent episodes of chest pain due to coronary artery vasospasm. The treatment of choice for an acute attack of Prinzmetal's angina involves medications that can rapidly relax vascular smooth muscle and restore blood flow to the heart.
**Why the Correct Answer is Right**
Nitrates, specifically nitroglycerin, are the agents of first choice in an acute attack of Prinzmetal's angina. Nitroglycerin works by releasing nitric oxide, which stimulates the enzyme guanylate cyclase, leading to increased levels of cyclic guanosine monophosphate (cGMP) in vascular smooth muscle cells. This results in smooth muscle relaxation, vasodilation, and a decrease in blood pressure, thereby relieving the spasm and restoring blood flow to the heart.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because calcium channel blockers, although useful in preventing coronary artery vasospasm, are not the first line of treatment for an acute attack of Prinzmetal's angina.
**Option B:** This option is incorrect because beta-blockers can actually worsen vasospasm and are contraindicated in Prinzmetal's angina.
**Option C:** This option is incorrect because antiplatelet agents, such as aspirin, are useful in preventing thrombotic events but do not address the underlying vasospasm.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that nitrates are the first line of treatment for acute Prinzmetal's angina due to their rapid onset of action and ability to relax vascular smooth muscle, restoring blood flow to the heart.
**Correct Answer:** A. Nitroglycerin