Management of Angina Pectoris
All patients with stable angina should immediately receive aspirin 75-100 mg daily, statin therapy, and beta-blockers as first-line therapy, combined with sublingual nitroglycerin for acute symptom relief and aggressive risk factor modification including mandatory smoking cessation. 1, 2
Dual Treatment Goals
Management of angina fundamentally requires two distinct therapeutic strategies that cannot be achieved with the same medications 1:
- Prognostic therapy (preventing MI and death): aspirin, statins, and ACE inhibitors—these do not alleviate symptoms 3, 1
- Symptomatic therapy (reducing angina and improving quality of life): antianginal drugs—these do not improve survival 1, 4
Pathophysiology
Angina results from myocardial ischemia when oxygen demand exceeds supply, typically due to coronary artery narrowing 5. Beta-blockers reduce oxygen requirements by blocking catecholamine-induced increases in heart rate, velocity and extent of myocardial contraction, and blood pressure 5. Up to 40% of patients may have microvascular angina (coronary microvascular dysfunction) rather than obstructive epicardial disease, explaining why ischemia can persist after successful revascularization 1.
Classification
The guidelines distinguish between 3:
- Chronic stable angina: predictable, reproducible chest pressure with exertion, relieved by rest or nitroglycerin 6
- Unstable angina: high to moderate short-term risk for acute coronary events—excluded from stable angina management protocols 3
Clinical Presentation
Classical angina symptoms are less reliable indicators of coronary disease in young and middle-aged women compared to men, compounded by higher prevalence of coronary artery spasm and Syndrome X in women 3. Look for:
- Predictable chest pressure or choking sensation with physical or emotional stress 6
- Relief with cessation of exertion or sublingual nitroglycerin 6
- Patients often avoid activities that precipitate symptoms 6
Clinical Examination & Diagnosis
Exercise ECG is the initial non-invasive test of choice to confirm diagnosis and determine prognosis 3, 1. The exercise ECG should be interpreted with attention to 3:
- Hemodynamic response
- Workload achieved
- Clinical features and symptoms
- ST-segment response
Alternative investigations are needed when exercise ECG is not possible, not interpretable, or when diagnosis remains uncertain 3:
- Myocardial perfusion scintigraphy—demonstrates extent and localization of ischemia 3, 1
- Stress echocardiography—demonstrates extent and localization of ischemia 3, 1
- Echocardiography or MRI—evaluates ventricular function 3
Do not perform exercise testing in patients with 3:
- Uncertain diagnosis requiring cardiologist referral (not direct exercise test referral) 3
- Physical incapacity for reasons other than angina 3
- Comorbid illness currently more important than angina 3
Pharmacological Management
Prognostic Medications (Preventing Death and MI)
Aspirin 75-100 mg daily is mandatory for all patients to reduce cardiovascular mortality and morbidity 3, 1, 2. Dosages of 75-150 mg daily and 160-325 mg daily show similar reduction in vascular events, but daily doses less than 75 mg have less benefit 3.
Clopidogrel 75 mg daily is reserved for patients who cannot take aspirin 3, 2. While clopidogrel appeared slightly more effective than aspirin in one trial, no further studies have confirmed efficacy specifically in stable angina 3.
Statin therapy should be initiated to achieve LDL-C <70 mg/dL when possible 3, 1, 2.
ACE inhibitors are indicated for patients with 3, 1:
- Coexisting ventricular dysfunction 3
- Hypertension 3
- Diabetes 3
- Prior MI with LV dysfunction 1
- Other high-risk features 3
Symptomatic Medications (Relieving Angina)
Beta-blockers should be used first-line as initial therapy for chronic stable angina 3, 1. They reduce cardiac events when used as secondary prevention in post-infarction patients and reduce mortality and morbidity among patients with hypertension 3. Target doses include 1:
Beta-blockers are particularly preferred in patients with 2, 7:
Calcium channel blockers (CCBs) are alternatives when beta-blockers are contraindicated, not tolerated, or cause persistent angina 3, 2, 7. Long-acting dihydropyridine and nondihydropyridine agents are generally as effective as beta-blockers in relieving angina 7. CCBs are preferred when beta-blockers are contraindicated 2.
Long-acting nitrates are considered third-line therapy because a nitrate-free interval is required to avoid tolerance 3, 7. They can be combined synergistically with beta-blockers to block reflex tachycardia 1. All long-acting nitrates appear equally effective 7. Nitrate patches should be used in dosages of at least 10 mg 3.
Short-acting nitrates (sublingual nitroglycerin) should be used for immediate symptom relief and situational prophylaxis 3, 1, 2. Patients should be instructed to sit during first use to prevent hypotension 1. Patients should take sublingual glyceryl trinitrate as required in response to pain and before engaging in activities that provoke angina 3.
Medication Optimization Strategy
Optimize the dosing of one drug before adding another, and switch drug combinations before attempting a three-drug regimen 3. Combinations should have additive or synergistic effects 1. Optimal monotherapy is often as effective as combination therapy 8.
Second-choice medications for patients with contraindications or inadequate response to first-line therapy include 1:
No direct comparisons have demonstrated superiority of first-choice over second-choice agents 1.
Critical Warnings for Beta-Blockers
Do not abruptly discontinue beta-blockers in patients with coronary artery disease—severe exacerbation of angina, MI, and ventricular arrhythmias have been reported 5. When discontinuing, reduce dosage gradually over 1-2 weeks and monitor carefully 5.
Beta-blockers may mask tachycardia occurring with hypoglycemia, though other manifestations like dizziness and sweating may not be significantly affected 5. Diabetes mellitus is not a contraindication to beta-blocker use 3.
Patients with bronchospastic disease should generally not receive beta-blockers, but metoprolol may be used due to relative beta-1 selectivity if other treatments fail 5. Use the lowest possible dose and consider administering smaller doses three times daily instead of larger doses twice daily 5.
Beta-blockers and nondihydropyridine calcium antagonists should not be used in patients with sinus bradycardia or greater than first-degree AV block due to risk of further heart rate slowing or high-grade AV block 8.
Lifestyle Modifications
Smoking cessation must be strongly emphasized as it directly impacts mortality 3, 2. Nicotine patches can safely be used to help patients with coronary artery disease stop smoking 3.
Aerobic physical activity of 150-300 minutes per week at moderate intensity or 75-150 minutes at vigorous intensity is recommended 2. Moderate exercise improves general fitness and wellbeing 3.
A Mediterranean diet with emphasis on vegetables, fruit, fish, and poultry is recommended 2. Fish consumption at least once weekly is recommended 2.
Patients with raised body mass index should reduce weight until BMI is normal 3.
Blood pressure should be measured and managed according to hypertension guidelines—hypertension accelerates atherosclerotic progression 3, 2.
Strict diabetic control and weight control are strongly advised 3.
Alcohol in moderation may be beneficial, but excessive consumption is harmful 2.
Revascularization
Coronary arteriography should be undertaken when symptoms are not satisfactorily controlled by medical means, with a view to revascularization 3.
Percutaneous Coronary Intervention (PCI) is effective for patients with angina not satisfactorily controlled by medical treatment when anatomically suitable lesions are present 3, 1. However, there is no evidence that PCI reduces the risk of death in patients with stable angina compared with medical or surgical therapy 3.
Coronary Artery Bypass Grafting (CABG) is highly effective for symptom relief and reduces mortality risk in specific subgroups 3, 1:
- Left main stem stenosis 3, 1
- Proximal LAD stenosis 3, 1
- Three-vessel disease, especially if LV function is impaired 3, 1
CABG is initially more effective in relieving angina than medical therapy, but the two yield similar results after 5-10 years 7. Eighty percent of patients who undergo CABG remain angina-free 5 years after surgery 7.
Patient Education
Patients must understand the nature of angina and when to seek emergency care, including alarm symptoms requiring immediate medical attention 2. Patients should rest briefly from activities that provoke angina 2. Patient education, cost-effectiveness, and patient preferences are important components in decision-making 3.
Common Pitfalls
Dipyridamole should not be used as an antiplatelet agent—usual oral doses can enhance exercise-induced myocardial ischemia in patients with stable angina 3.
Triple therapy may be deleterious and no more effective than dual therapy 8.
Exercise testing has low diagnostic usefulness in patients with low pretest probability of coronary artery disease 3. When requesting exercise testing on a patient with diabetes, this should be clearly stated on the request form as it influences test performance or interpretation 3.
Many individuals with stable angina are not referred for functional testing to confirm diagnosis and determine prognosis—a gap between best practice and usual care 3.