From the Guidelines
Prinzmetal angina is a rare form of chest pain caused by coronary artery spasm rather than blockages from atherosclerosis, and treatment primarily involves calcium channel blockers like diltiazem (180-360 mg daily) or amlodipine (5-10 mg daily), which are first-line therapy because they effectively prevent coronary vasospasm. It typically occurs at rest, often during sleep or early morning hours, and is characterized by transient ST-segment elevation on ECG during episodes 1.
Key Characteristics
- Transient ST-segment elevation on ECG during episodes
- Occurs at rest, often during sleep or early morning hours
- Relieved by nitrates within minutes
- May coexist with typical exertional angina due to fixed coronary lesions
Diagnosis and Treatment
- Diagnosis is confirmed by documenting ST elevation during pain episodes or through provocative testing with acetylcholine or ergonovine during coronary angiography 2
- Treatment involves calcium channel blockers and long-acting nitrates such as isosorbide mononitrate (30-60 mg daily) for symptom control
- Patients should avoid potential triggers including smoking, cocaine, and certain medications that can induce vasospasm
- Beta-blockers may worsen Prinzmetal angina and should generally be avoided
Prognosis
- The prognosis is generally favorable with appropriate medical therapy, though some patients may experience myocardial infarction or life-threatening arrhythmias during severe episodes, making proper diagnosis and treatment essential 3
- A substantial proportion of patients with a history suggestive of vasospastic angina have obstructive coronary disease, and in such patients, vasospastic angina may coexist with typical exertional angina due to fixed coronary lesions.
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 indicated for the treatment of Prinzmetal's angina.
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 7.
- It is diagnosed by history, electrocardiogram, or coronary-artery angiography 7.
- Provocative tests, such as the cold-pressor test or intravenous ergonovine maleate, are sometimes used to aid diagnosis of PVA 7.
Treatment of Prinzmetal Angina
- Nitrates, adrenergic-blocking agents, and calcium-channel blocking agents can be used in treating PVA 7.
- Nitroglycerin and isosorbide dinitrate effectively relieve CAS 7.
- Calcium-channel blocking agents are promising drugs for PVA, with nifedipine being the prototype of this class for antianginal activity 7, 8.
- Verapamil hydrochloride is effective for PVA, but only 10-20% of an orally administered dose reaches systemic circulation due to the first-pass effect 7.
- Therapy using combinations of nitrates, adrenergic-blocking agents, and calcium-channel blocking agents is needed in some patients 7.
Role of Calcium Channel Blockers
- Calcium channel blockers are used extensively in the treatment of the three major anginal syndromes, including Prinzmetal's angina 9.
- In the treatment of Prinzmetal's angina, their antivasospastic properties account for their therapeutic effectiveness 9.
- Calcium channel blockers are drugs of first choice in Prinzmetal's angina 9.
- Vascular-selective dihydropyridines, such as felodipine, have been introduced recently and offer advantages over nonselective calcium channel blockers, particularly in patients receiving beta-blockers 9.
Combination Therapy
- Combination therapy with calcium antagonists, beta-blockers, and nitrates is effective in reducing ischemic episodes in patients with unstable angina 10, 11.
- Nifedipine used with beta-blocker drugs is more effective than nifedipine as monotherapy in patients with unstable angina 11.
- Diltiazem and verapamil have been shown to be effective when given without beta-blockers in unstable angina patients 11.
Silent Myocardial Ischemia
- Episodes of silent or asymptomatic myocardial ischemia occur in a variety of disorders of coronary disease, including Prinzmetal's variant angina and unstable angina 10.
- Calcium antagonists are effective in decreasing episodes of ischemia regardless of the presence or absence of symptoms 10.
- Persisting episodes of silent ischemia among patients with unstable angina despite maximal medical therapy identify patients at high risk for an early unfavorable outcome 10.