Prinzmetal Angina and Coronary Vasospasm
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Direct answer
Prinzmetal angina is a variant angina caused by focal coronary artery vasospasm, typically at rest and often in the early morning, with transient ST elevation during the episode. Coronary angiography may show normal arteries or only fixed stenosis, so provocation testing with intracoronary acetylcholine or ergonovine is used to reproduce the spasm. Calcium channel blockers and nitrates form the mainstay of treatment, while beta-blockers are avoided because they can worsen spasm.
What you must remember
- Mechanism: focal, reversible spasm of a coronary artery, which can occur on normal or atherosclerotic vessels.
- Presentation: recurrent rest angina, often at night or in the early morning, which may be severe.
- ECG: transient ST elevation during the attack that settles with nitrates or pain relief, sometimes with arrhythmia.
- Provocation: intracoronary acetylcholine or ergonovine reproduces spasm when angiography is non-diagnostic.
- Triggers: smoking and cocaine are classic triggers, and stress or cold exposure may also provoke spasm.
- Treatment: calcium channel blockers such as amlodipine or nifedipine, long-acting nitrates and smoking cessation.
- Avoid: beta-blockers, because unopposed alpha-adrenergic vasoconstriction can worsen spasm.
- Prognosis: arrhythmia, MI and sudden death are the main complications, especially with ongoing smoking.
Working up night-time chest pain with transient ST elevation
A 52-year-old smoker wakes at 4 am with chest pain, and his ECG shows ST elevation in the inferior leads that settles after sublingual nitrate. The examiner wants the candidate to separate vasospasm from acute coronary occlusion.
- Exclude acute coronary syndrome: Serial troponin and repeat ECGs are checked, because persistent ST elevation with a troponin rise is STEMI until proven otherwise.
- Image the coronaries: Angiography may show normal arteries or fixed stenosis, and the operator looks for spasm within the vessel.
- Provoke the spasm: Intracoronary acetylcholine or ergonovine is given in the laboratory, with intracoronary nitrate available to reverse the spasm.
- Start a calcium channel blocker: Amlodipine or nifedipine is started and titrated, with a long-acting nitrate added if pain persists.
- Remove the triggers: Smoking cessation and avoidance of cocaine are central to long-term control.
- Review beta-blockers: A beta-blocker given for another indication is reviewed if spasm recurs, since it may provoke further attacks.
Where the exam tries to catch you
Vasospasm questions test the drug choice and the differential diagnosis.
- Trap: Giving a beta-blocker for presumed ACS in a patient with rest angina. Correct: Beta-blockers can precipitate spasm, so calcium channel blockers are the correct choice.
- Trap: Assuming any chest pain with ST elevation is Prinzmetal angina. Correct: Persistent ST elevation with a troponin rise is STEMI, and vasospasm is diagnosed only after exclusion.
- Trap: Treating a normal angiogram as proof that the coronaries are healthy. Correct: Spasm may be silent at rest and only provoked by testing, so provocation is needed.
- Trap: Treating ergonovine or acetylcholine as therapy. Correct: They are diagnostic provocation agents used in the catheter laboratory, not treatment.
Frequently asked questions
Why are beta-blockers avoided in Prinzmetal angina?
Beta-blockers are avoided in Prinzmetal angina because unopposed alpha-adrenergic stimulation can worsen coronary vasospasm. Calcium channel blockers and nitrates are preferred, since they relax the coronary smooth muscle that is spasming.
Which drugs are used to treat coronary vasospasm?
Calcium channel blockers such as amlodipine or nifedipine and long-acting nitrates are the mainstay for coronary vasospasm. Smoking cessation and avoidance of cocaine are also central, because these triggers can repeatedly provoke spasm.
Which agents confirm coronary vasospasm during angiography?
Intracoronary acetylcholine or ergonovine is used to provoke coronary spasm during angiography when the diagnosis is unclear. Intracoronary nitrate is kept available to reverse the spasm once the diagnosis is confirmed.
What are the classic triggers of Prinzmetal angina?
Smoking and cocaine use are classic triggers of Prinzmetal angina, and stress or cold exposure may also precipitate attacks. Identifying and removing these triggers is part of long-term management.