First-Line Medication for Prinzmetal's Angina
Calcium channel blockers and long-acting nitrates are the first-line medications for Prinzmetal's (variant) angina, with calcium channel blockers generally preferred due to their sustained 24-hour effects and superior efficacy in preventing coronary vasospasm. 1
Acute Management
- Sublingual nitroglycerin (0.3-0.4 mg) or isosorbide dinitrate (5-10 mg) should be used for immediate relief of acute vasospastic episodes, with repeat dosing after 3-5 minutes if pain persists 2
- For refractory cases, sublingual nifedipine (5-10 mg) or intravenous nitrates/calcium antagonists can be administered 2
- During coronary angiography, 0.3 mg of nitroglycerin should be infused directly into the involved coronary artery if spasm develops 1
Chronic Preventive Therapy
Calcium Channel Blockers (First Choice)
Calcium channel blockers are considered first-line therapy because they directly block coronary artery vasospasm through inhibition of calcium influx into vascular smooth muscle 1, 3. The mechanism is particularly effective for vasospastic angina, as amlodipine and other calcium antagonists block constriction and restore blood flow in coronary arteries in response to multiple vasoconstrictor stimuli 3.
Recommended dosing regimens:
- Verapamil: 240-480 mg per day 1
- Diltiazem: 180-360 mg per day 1
- Nifedipine: 60-120 mg per day 1
- Amlodipine: 5-10 mg once daily 3
Clinical efficacy: Nifedipine, diltiazem, and verapamil are all highly and equally effective in reducing painful and painless ischemic episodes in Prinzmetal's variant angina 4. In long-term studies, calcium channel blockers abolished symptoms and chronic ischemic episodes in 81% of treated subjects 5.
Long-Acting Nitrates (Alternative First Choice)
Long-acting nitrates are also considered first-line therapy and can be used when calcium channel blockers are not tolerated 1. However, calcium channel blockers are often preferable because of their sustained 24-hour effects without the need for nitrate-free intervals 1.
Combination Therapy
Patients with very active disease may require combination therapy with both nitrates and calcium channel blockers of different classes (e.g., a dihydropyridine with verapamil or diltiazem) 1. Alpha-receptor blockers have been reported beneficial in patients not responding completely to calcium channel blockers and nitrates 1.
Critical Contraindications
Beta-blockers are contraindicated in vasospastic angina because they can result in coronary constriction by causing a shift from β-adrenoreceptors to α-adrenoceptors, leading to unopposed alpha-mediated vasoconstriction 1. While beta-blockers have theoretical adverse potential, their clinical effect remains controversial 1.
Additional Management
- Smoking cessation is mandatory as smoking is a known trigger for coronary vasospasm 1
- The prognosis is usually excellent with medical therapy, especially in patients with normal or near-normal coronary arteries, with 5-year survival rates of 89-97% 1
- Patients with coronary artery vasospasm superimposed on fixed obstructive CAD have worse prognosis and may require more aggressive management 1