From the Guidelines
Prinzmetal angina is a rare form of chest pain caused by coronary artery spasm rather than blockages from atherosclerosis, and treatment focuses on calcium channel blockers like diltiazem (30-90mg three to four times daily) or amlodipine (5-10mg daily), which are first-line therapy because they effectively prevent coronary vasospasm. This condition typically occurs at rest, often during sleep or early morning hours, and is characterized by transient ST-segment elevation on ECG during episodes 1. The diagnosis of Prinzmetal angina is confirmed by documenting ST elevation during pain episodes or through provocative testing with acetylcholine or ergonovine during cardiac catheterization 1.
Some key points to consider in the management of Prinzmetal angina include:
- Avoiding potential triggers such as smoking, cocaine, and certain medications that can induce vasospasm 1
- Using long-acting nitrates such as isosorbide mononitrate (30-60mg daily) or isosorbide dinitrate (20-40mg twice daily) as adjunctive therapy 1
- Avoiding beta-blockers, which may worsen Prinzmetal angina 1
- Considering high doses or combinations of vasodilators for symptom control in patients who do not respond to initial therapy 1
The underlying mechanism of Prinzmetal angina involves hyperreactivity of vascular smooth muscle in coronary arteries, leading to abnormal constriction and temporary reduction in blood flow to the heart muscle 1. Overall, the goal of treatment is to prevent coronary vasospasm and reduce the frequency and severity of episodes of chest pain. The most effective treatment strategy is to use a combination of calcium channel blockers and long-acting nitrates, and to avoid potential triggers and beta-blockers.
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, also known as vasospastic angina.
- The medication works by blocking the constriction of coronary arteries and arterioles, thereby restoring blood flow.
- This effect is due to amlodipine's ability to inhibit the influx of calcium ions into vascular smooth muscle and cardiac muscle.
- The use of amlodipine in Prinzmetal's angina has been demonstrated in clinical trials to decrease the frequency of angina attacks 2, 2, 2.
From the Research
Definition and Diagnosis of Prinzmetal Angina
- Prinzmetal angina, also known as variant angina, 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, and provocative tests such as the cold-pressor test or intravenous ergonovine maleate may be used to aid diagnosis 3.
Treatment of Prinzmetal Angina
- Nitrates, adrenergic-blocking agents, and calcium-channel blocking agents can be used in treating Prinzmetal angina 3.
- Calcium-channel blocking agents, such as nifedipine, diltiazem, and verapamil, are highly effective in reducing painful and painless ischemic episodes in Prinzmetal's variant angina 4, 5.
- Nifedipine is generally considered the prototype of this class for antianginal activity and is effective in preventing episodes of coronary vasospasm and symptoms of ischemia 3, 6.
- Verapamil hydrochloride is also effective for Prinzmetal angina, but its use is limited by the first-pass effect, which reduces its systemic circulation 3.
Combination Therapy
- Combination therapy using nitrates, adrenergic-blocking agents, and calcium-channel blocking agents may be needed in some patients with Prinzmetal angina 3.
- Nifedipine used with beta-blocker drugs is more effective than nifedipine as monotherapy in patients with unstable angina 4.
- A combination regimen of calcium antagonists, beta blockers, and nitrates may be more effective than either form of therapy alone in controlling angina 5.
Silent Myocardial Ischemia
- Calcium antagonists are effective in decreasing episodes of silent ischemia in patients with Prinzmetal's variant angina and unstable angina, regardless of the presence or absence of symptoms 5.
- Persisting episodes of silent ischemia among patients with unstable angina despite maximal medical therapy identify patients at high risk for an early unfavorable outcome 5.