What is the relationship between Variant angina (Prinzmetal's angina) and ST-Elevation Myocardial Infarction (STEMI)?

From the Guidelines

Prinzmetal angina can mimic a STEMI on ECG but does not typically cause a true STEMI, and treatment should focus on relieving vasospasm with calcium channel blockers and nitrates, rather than thrombolytic therapy. Prinzmetal angina, also called variant angina, is caused by coronary artery vasospasm rather than plaque rupture or thrombosis 1. The underlying mechanisms of spasm induction are still unclear, but local hyper-reactivity of coronary smooth muscle to various constrictor stimuli may be involved 1.

Key Considerations

• Treatment focuses on calcium channel blockers (such as diltiazem 30-90mg three times daily or amlodipine 5-10mg daily) and long-acting nitrates (like isosorbide mononitrate 30-60mg daily) 1.
• During acute episodes, sublingual nitroglycerin 0.4mg can provide immediate relief 1.
• Avoid beta-blockers as they may worsen vasospasm 1.
• Patients should undergo coronary angiography to rule out significant coronary artery disease 1.
• The distinction between Prinzmetal angina and true STEMI is crucial because Prinzmetal angina doesn't typically lead to myocardial necrosis if treated promptly 1.

Additional Recommendations

• Patients with Prinzmetal angina should avoid triggers like smoking, cocaine, and alcohol, which can precipitate vasospasm 1.
• Provocative testing, such as ergonovine or hyperventilation, may be considered in patients with a nonobstructive lesion on coronary arteriography and suspected coronary spasm 1.
• Treatment with nitrates and calcium antagonists is recommended in patients whose coronary arteriogram is normal or shows only nonobstructive lesions 1.

From the FDA Drug Label

Verapamil hydrochloride dilates the main coronary arteries and coronary arterioles, both in normal and ischemic regions, and is a potent inhibitor of coronary artery spasm, whether spontaneous or ergonovine-induced This property increases myocardial oxygen delivery in patients with coronary artery spasm and is responsible for the effectiveness of verapamil hydrochloride in vasospastic (Prinzmetal’s or variant) as well as unstable angina at rest

Verapamil can be used to treat Prinzmetal's angina, which is caused by coronary artery spasm. However, it is not explicitly stated in the label whether verapamil can prevent STEMI (ST-Elevation Myocardial Infarction) in patients with Prinzmetal's angina.

• The label does mention that verapamil increases myocardial oxygen delivery in patients with coronary artery spasm, which may help reduce the risk of STEMI.
• However, without direct evidence, it is unclear whether verapamil can effectively prevent STEMI in patients with Prinzmetal's angina 2.

From the Research

Prinzmetal Angina and STEMI

• Prinzmetal's angina, also known as variant angina, is a temporary increase in coronary vascular tone (vasospasm) causing a marked, but transient reduction in luminal diameter 3.
• This condition can lead to recurrent ST elevation myocardial infarction (STEMI) and should be considered in patients with both typical and atypical cardiovascular risk profiles 4.
• The diagnosis of Prinzmetal's angina is made by observing transient ST-segment elevation during the attack of angina, and the most sensitive and specific test for diagnosis is the administration of ergonovine intravenously 3.

Characteristics of Prinzmetal Angina

• Patients with Prinzmetal's angina are predominantly younger women who may not have the classical cardiovascular risk factors (except for cigarette use) 3.
• The condition is associated with vasospastic disorders such as Raynaud's phenomenon and migraine headaches, and arrhythmias are common and may be life-threatening 3.
• Endothelial dysfunction is considered primarily responsible for Prinzmetal's angina 3.

Treatment of Prinzmetal Angina

• Medical therapy for Prinzmetal's angina classically employs vasodilator drugs, which include nitrates and calcium channel blockers 3, 5.
• Calcium antagonists, such as nifedipine, diltiazem, and verapamil, are highly effective in reducing ischemic episodes in patients with Prinzmetal's angina 6, 7.
• Beta-blockers and large doses of aspirin are contraindicated in Prinzmetal's angina 3.