Mastering Medical
USMLE Step 1 · Cardiovascular

Stable and unstable angina vs Prinzmetal angina

How to tell Stable and unstable angina and Prinzmetal angina apart when a board question makes them look alike.

Fastest separator

Stable/unstable angina is plaque-demand or ACS pattern; Prinzmetal is vasospasm with transient ST elevation.

Side by side

Stable and unstable anginaPrinzmetal angina
Key clue

Stable is predictable exertional pain relieved by rest; unstable is new, worsening, or rest pain without troponin elevation.

Episodic rest pain from coronary vasospasm with transient ST elevation, often relieved by nitrates or calcium channel blockers.

Mechanism

Fixed plaque limits flow during demand in stable angina; plaque instability causes ACS physiology in unstable angina.

Transient coronary artery spasm reduces flow despite no fixed critical stenosis requirement.

Labs and tests

Predictable exertion pattern points stable; rest/crescendo pain with negative troponin points unstable angina.

Transient ST elevation during pain with vasospasm triggers such as smoking or cocaine points Prinzmetal.

The trap

Rest pain can be unstable angina or Prinzmetal; transient ST elevation that resolves with vasodilators is the spasm clue.

Watch it explained

In the rapid reviewMI Made Easy for USMLE Step 1: STEMI, NSTEMI, Prinzmetal & Aortic Dissection
Test it now

The repair move

For angina, ask pattern first: predictable exertion, crescendo/rest ACS, or episodic vasospasm.

Try a free question

Core

A patient has predictable substernal chest pressure while climbing stairs that resolves with rest or nitroglycerin. Troponin is negative and symptoms are unchanged for months. Which diagnosis is most likely?

Show answer and explanation

Answer: A. Stable angina. Stable angina is exertional, predictable, and relieved by rest or nitrates without troponin elevation.

Why the other choices are tempting

  • B. Unstable angina is new, worsening, or rest pain without troponin elevation.
  • C. Prinzmetal angina is episodic rest pain from coronary vasospasm with transient ST elevation.
  • D. NSTEMI has troponin elevation.
  • E. Pericarditis causes positional pleuritic pain with diffuse ST elevation and PR depression.

Flashcards

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What is the fastest separator for Stable and unstable angina vs Prinzmetal angina?

Stable/unstable angina is plaque-demand or ACS pattern; Prinzmetal is vasospasm with transient ST elevation.

What clue should make you choose Stable and unstable angina?

Stable is predictable exertional pain relieved by rest; unstable is new, worsening, or rest pain without troponin elevation.

Quick answers

What is the fastest way to tell Stable and unstable angina from Prinzmetal angina?

Stable/unstable angina is plaque-demand or ACS pattern; Prinzmetal is vasospasm with transient ST elevation.

What is the key clue for Stable and unstable angina?

Stable is predictable exertional pain relieved by rest; unstable is new, worsening, or rest pain without troponin elevation.

What is the key clue for Prinzmetal angina?

Episodic rest pain from coronary vasospasm with transient ST elevation, often relieved by nitrates or calcium channel blockers.

What is the common trap with Stable and unstable angina vs Prinzmetal angina?

Rest pain can be unstable angina or Prinzmetal; transient ST elevation that resolves with vasodilators is the spasm clue.