What is the diagnosis and treatment for Variant angina (Prinzmetal's angina)?

From the Guidelines

Prinzmetal angina should be treated with calcium channel blockers like diltiazem (180-360 mg daily) or amlodipine (5-10 mg daily) as first-line therapy, with long-acting nitrates such as isosorbide mononitrate (30-120 mg daily) often added for additional relief, as this approach has been shown to be effective in managing the condition and improving quality of life 1.

Key Considerations

• Prinzmetal angina is a rare form of chest pain caused by coronary artery spasm rather than blockages from atherosclerosis.
• It typically occurs at rest, often during sleep or early morning hours, and is characterized by transient ST-segment elevation on ECG during episodes.
• Beta-blockers should be avoided as they can worsen coronary spasms.
• Patients should stop smoking immediately as it significantly increases risk of spasm.
• Unlike typical angina, Prinzmetal angina doesn't consistently respond to physical exertion and can affect people with otherwise normal coronary arteries.

Diagnostic Approach

• Diagnostic tests for Prinzmetal’s angina are based on the recording of transient ST-segment elevation during an episode of chest pain.
• Continuous 12-lead ECG monitoring can be performed for this purpose in-hospital or as an outpatient; recording during numerous episodes of pain improves diagnostic sensitivity.
• A treadmill exercise test is also useful; one third of patients will show ST-segment elevation, another third ST-segment depression, and one third no ST-segment change.

Treatment Goals

• The goal of treatment is to relieve symptoms, prevent recurrent episodes, and reduce the risk of complications such as arrhythmias or myocardial infarction.
• Treatment should be individualized based on the patient's specific needs and circumstances.
• Regular follow-up and monitoring are essential to adjust treatment as needed and to prevent complications.

Additional Recommendations

• Patients with Prinzmetal angina should be educated on the importance of lifestyle modifications, such as quitting smoking and managing stress, to help manage their condition.
• They should also be instructed on how to recognize and respond to episodes of chest pain, including taking medication as prescribed and seeking medical attention if symptoms worsen or persist.

From the FDA Drug Label

Amlodipine besylate tablets is indicated for the treatment of confirmed or suspected vasospastic angina. Amlodipine has been demonstrated to block constriction and restore blood flow in coronary arteries and arterioles in response to calcium, potassium epinephrine, serotonin, and thromboxane A2 analog in experimental animal models and in human coronary vessels in vitro This inhibition of coronary spasm is responsible for the effectiveness of amlodipine in vasospastic (Prinzmetal's or variant) angina.

Amlodipine is effective in treating Prinzmetal's angina by blocking coronary spasm and restoring blood flow in coronary arteries.

• The drug has been shown to be effective in reducing the frequency of angina attacks in patients with vasospastic angina.
• Amlodipine works by inhibiting the influx of calcium ions into vascular smooth muscle and cardiac muscle, which helps to prevent coronary spasm.
• The effectiveness of amlodipine in treating Prinzmetal's angina has been demonstrated in several clinical trials, including a double-blind, placebo-controlled study that showed a significant reduction in angina attacks with amlodipine therapy 2, 2, 2.

From the Research

Definition and Diagnosis of Prinzmetal Angina

• Prinzmetal's variant angina (PVA) is a form of angina caused by coronary-artery vasospasm (CAS) and is not associated with exertion 3.
• It is diagnosed by history, electrocardiogram, or coronary-artery angiography 3.
• Provocative tests, such as the cold-pressor test or intravenous ergonovine maleate, are sometimes used to aid diagnosis of PVA 3.

Treatment of Prinzmetal Angina

• Nitrates, adrenergic-blocking agents, and calcium-channel blocking agents can be used in treating PVA 3.
• Nitroglycerin and isosorbide dinitrate effectively relieve CAS 3.
• Calcium-channel blocking agents are promising drugs for PVA, with nifedipine being the prototype of this class for antianginal activity 3, 4, 5.
• Verapamil hydrochloride is effective for PVA, but only 10-20% of an orally administered dose reaches systemic circulation because of the first-pass effect 3.
• Felodipine, a vascular-selective dihydropyridine, has been shown to be effective in treating PVA, with no negative inotropic effects at clinically administered doses 4.

Calcium Channel Blockers in Prinzmetal Angina

• Calcium channel blockers are used extensively in the treatment of Prinzmetal's angina, with their antivasospastic properties accounting for their therapeutic effectiveness 4, 5.
• Nifedipine, diltiazem, and verapamil are all highly and equally effective in reducing painful and painless ischemic episodes in Prinzmetal's variant angina 5.
• Calcium antagonists provide a unique tool to reduce myocardial oxygen demand and prevent increases in coronary vasomotor tone 6.

Combination Therapy and Silent Myocardial Ischemia

• Combination therapy with calcium channel blockers, beta-blockers, and nitrates may be more effective than monotherapy in treating unstable angina 5, 6.
• Calcium antagonists are effective in decreasing episodes of silent ischemia in patients with Prinzmetal's variant angina and unstable angina 6.
• Persisting episodes of silent ischemia among patients with unstable angina despite maximal medical therapy identify patients at high risk for an early unfavorable outcome 6.