What is the treatment for Prinzmetal's (variant) angina?

Treatment for Prinzmetal's (Variant) Angina

Calcium channel blockers and nitrates are the first-line treatments for Prinzmetal's angina, with calcium channel blockers often requiring moderate to high doses for effective management of coronary vasospasm. 1

Diagnosis and Clinical Features

Before discussing treatment, it's important to understand the diagnostic criteria for Prinzmetal's angina:

• Transient ST-segment elevation during episodes of chest pain (typically at rest)
• Pain that resolves spontaneously or rapidly with nitroglycerin
• Circadian pattern with attacks often occurring in early morning hours
• May occur in patients with normal coronary arteries or with atherosclerotic lesions

Diagnostic confirmation can be achieved through:

• Documentation of ST-segment elevation during chest pain
• Coronary angiography (Class I recommendation) 1
• Provocative testing with ergonovine in selected cases (Class IIb) 1

Treatment Algorithm

First-Line Therapy:

1. Calcium Channel Blockers (Class I) 1

   • Often required at moderate to high doses:

     • Verapamil: 240-480 mg daily
     • Diltiazem: 180-360 mg daily
     • Nifedipine: 60-120 mg daily
     • Amlodipine: 5-10 mg daily 2

   • Calcium channel blockers are highly effective in preventing coronary spasm by blocking calcium influx into vascular smooth muscle 3

   • Amlodipine specifically blocks constriction and restores blood flow in coronary arteries in response to various vasoconstrictive stimuli 2

2. Nitrates (Class I) 1

   • Short-acting nitrates (nitroglycerin) for acute attacks
   • Long-acting nitrates for prevention
   • Often used in combination with calcium channel blockers
   • Extremely effective in relieving acute spasm

For Refractory Cases:

1. Combination Therapy

   • Nitrates plus two calcium channel blockers of different classes (e.g., dihydropyridine with verapamil or diltiazem) 1
   • Medication schedule should be adapted to the circadian variation of spasm episodes 1

2. Alpha-Receptor Blockers

   • May be beneficial in patients not responding completely to calcium channel blockers and nitrates 1

3. Consider Stent Implantation

   • For focal refractory spasm 1

Special Considerations

• Beta-blockers: Generally contraindicated or used with caution as they have theoretical adverse potential and may worsen vasospasm 1, 4

• Aspirin: Large doses should be avoided 4

• Risk factor modification: Essential, especially smoking cessation 1

• Underlying coronary disease: Patients with significant coronary stenosis in addition to vasospasm have worse prognosis and may require additional interventions 1

Prognosis

The prognosis for Prinzmetal's angina is generally favorable with appropriate treatment:

• 5-year survival rate: 89-97% overall 1
• Better prognosis in patients with normal or near-normal coronary arteries 1
• Annual risk of myocardial infarction: approximately 1.2% 1
• Annual risk of cardiovascular death: approximately 0.5% 1

Common Pitfalls to Avoid

1. Undertreatment: Vasospasm often requires higher doses of calcium channel blockers than typical angina

2. Discontinuing medications: Abrupt withdrawal can lead to rebound spasm and myocardial infarction 5

3. Overreliance on exercise testing: Unlike typical angina, exercise testing has limited value in diagnosis as attacks typically occur at rest

4. Missing the diagnosis: Prinzmetal's angina can be mistaken for other causes of chest pain if ST elevation isn't captured during an episode

5. Inappropriate use of beta-blockers: These may worsen vasospasm and should be used cautiously, if at all

By following this treatment approach focused on calcium channel blockers and nitrates, most patients with Prinzmetal's angina can achieve good symptom control and favorable long-term outcomes.