Does amlodipine help with Prinzmetal's (variant) angina?

Amlodipine for Prinzmetal's (Variant) Angina

Amlodipine is highly effective for treating Prinzmetal's angina and is specifically indicated for the treatment of confirmed or suspected vasospastic angina. 1

Mechanism of Action in Vasospastic Angina

• Amlodipine blocks constriction and restores blood flow in coronary arteries by inhibiting the transmembrane influx of calcium ions into vascular smooth muscle cells 1
• This inhibition of coronary spasm is directly responsible for amlodipine's effectiveness in vasospastic (Prinzmetal's) angina 1
• As a dihydropyridine calcium channel blocker, amlodipine prevents the focal coronary artery spasm that characterizes Prinzmetal's angina 2

Evidence Supporting Amlodipine's Efficacy

• FDA labeling specifically indicates amlodipine for "the treatment of confirmed or suspected vasospastic angina" as either monotherapy or in combination with other antianginal agents 1
• In a clinical trial of 50 patients with vasospastic angina, amlodipine therapy decreased anginal attacks by approximately 4/week compared to placebo (p<0.01) 1
• Calcium channel blockers, including amlodipine, are highly effective in reducing both painful and painless ischemic episodes in Prinzmetal's variant angina 2
• Amlodipine has been shown to be consistently effective in patients with vasospastic angina with no evidence of tolerance to its anti-anginal effects in clinical trials lasting up to 26 weeks 3

Treatment Approach for Prinzmetal's Angina

• First-line therapy for coronary spasm includes calcium channel blockers and nitrates 4
• Treatment recommendations from guidelines:
  • Calcium channel blockers and nitrates are recommended as first-line therapies for patients with variant angina whose coronary angiogram shows no or nonobstructive coronary artery lesions 4
  • Usually, a calcium channel blocker in moderate to high dose is started; patients with very active disease may require a combination of nitrates and calcium channel blockers 4

Dosing and Administration

• Start with amlodipine 5 mg once daily 3
• Increase to 10 mg daily if required to control symptoms 3
• Amlodipine's long elimination half-life makes it suitable for once-daily dosing with anti-anginal efficacy lasting a full 24 hours 3

Clinical Considerations and Potential Pitfalls

• Beta-blockers have theoretical adverse potential in vasospastic angina and their clinical effect is controversial - they should generally be avoided 4
• Patients with coronary artery vasospasm superimposed on fixed obstructive coronary artery disease have a worse prognosis and may require more aggressive therapy 4
• Smoking cessation is essential as smoking is a risk factor for Prinzmetal's angina 4
• For patients not responding completely to calcium channel blockers and nitrates, alpha-receptor blockers have been reported to be beneficial 4
• In patients with very active disease, a combination of nitrates and two calcium channel blockers of different classes (i.e., a dihydropyridine like amlodipine with verapamil or diltiazem) may be required 4

Case Example

• A case report described a 67-year-old male with recurrent ST-elevation and chest pain who was found to have coronary vasospasm. After initiation of therapy with amlodipine and isosorbide mononitrate, the patient remained symptom-free at subsequent follow-up visits 5

Monitoring and Follow-up

• Monitor for resolution of anginal episodes and ST-segment changes on ECG 4
• Amlodipine does not typically cause significant changes in heart rate or ECG parameters in patients with angina 1
• Be aware that Prinzmetal's angina often occurs in clusters with prolonged asymptomatic periods, so long-term therapy may be necessary despite symptom-free intervals 4