What is the treatment approach for a patient presenting with symptoms of stable vs unstable angina, considering their individual medical history and risk factors?

Treatment Approach: Stable vs Unstable Angina

The fundamental distinction between stable and unstable angina determines immediate management: unstable angina requires urgent hospitalization with intensive medical therapy and risk stratification for early invasive intervention, while stable angina can be managed with outpatient medical optimization and elective stress testing. 1

Immediate Risk Stratification

Unstable Angina Recognition

• Admit any patient with rest angina lasting >20 minutes, new-onset severe angina (Canadian Cardiovascular Society Class III-IV within 2 weeks), or accelerating angina pattern to a monitored bed or intensive care unit. 1
• High-risk features requiring immediate intensive care admission include: pulmonary edema related to ischemia, new or worsening mitral regurgitation murmur, S3 gallop or new rales, hypotension/bradycardia/tachycardia, transient ST-segment changes ≥0.05 mV during pain, new bundle branch block, sustained ventricular tachycardia, or elevated troponin (>0.1 mg/mL). 1
• Intermediate-risk patients (prolonged rest angina now resolved, age >70 years, T-wave inversions >0.2 mV, pathological Q waves, slightly elevated troponin 0.01-0.1 mg/mL) can be managed in monitored hospital beds. 1

Stable Angina Identification

• Patients with new-onset angina provoked only by exertion (walking 1 block or climbing 1 flight of stairs), normal or unchanged ECG during chest discomfort, and normal cardiac biomarkers qualify as low-risk and can be managed outpatient. 1
• Stable angina is characterized by predictable chest discomfort with exertion that is relieved by rest or nitroglycerin within minutes, without rest symptoms or accelerating pattern. 1, 2

Unstable Angina: Immediate Treatment Protocol

First-Line Pharmacotherapy (Within Minutes)

• Administer aspirin 162-325 mg immediately (chewed for faster absorption), followed by 75-162 mg daily indefinitely. 1
• Start clopidogrel with 300 mg loading dose, then 75 mg daily for at least 18 months. 1
• Initiate anticoagulation immediately with unfractionated heparin (60 units/kg bolus for patients <70 kg, then 12 units/kg/hour infusion targeting aPTT 50-70 seconds) or low-molecular-weight heparin (enoxaparin preferred). 1
• Give sublingual nitroglycerin 0.4 mg every 5 minutes up to 3 doses; if pain persists, start intravenous nitroglycerin 10-20 mcg/min. 1
• Administer beta-blockers (metoprolol 25-50 mg orally every 6-12 hours or IV 5 mg every 5 minutes for 3 doses) unless contraindicated by heart failure, bradycardia, or hypotension. 1

Glycoprotein IIb/IIIa Inhibitors for High-Risk Patients

• Add eptifibatide (180 mcg/kg bolus followed by 2 mcg/kg/min infusion) or tirofiban for patients with elevated troponin, persistent ST-segment changes, or planned early percutaneous coronary intervention within 24-48 hours. 3
• Continue eptifibatide infusion for 72 hours or until hospital discharge, extending to 18-24 hours post-PCI if intervention performed. 3

Invasive vs Conservative Strategy Decision

• Proceed with early invasive strategy (coronary angiography within 4-24 hours) for patients with refractory angina despite medical therapy, hemodynamic instability, elevated troponin, dynamic ST-segment changes, diabetes mellitus, or reduced left ventricular function. 1
• Conservative strategy with stress testing after 2-3 days of stabilization is appropriate only for low-risk patients (normal ECG, normal biomarkers, no high-risk features) who respond completely to medical therapy. 1

Stable Angina: Outpatient Management Approach

Initial Diagnostic Workup

• Obtain resting 12-lead ECG in all patients, though recognize that >50% of chronic stable angina patients have normal resting ECGs. 1, 2
• Perform stress testing within 72 hours of presentation using standard exercise ECG (Bruce protocol with Duke treadmill score) for patients with intermediate pretest probability, interpretable ECG, and ability to exercise. 1, 2
• Use stress imaging (nuclear or echocardiography) for patients with uninterpretable baseline ECG, inability to exercise, or when localization of ischemia is needed. 1, 2

Medical Therapy Optimization

• Start aspirin 75 mg daily for at least 4 years, then continue indefinitely. 1
• Initiate beta-blocker as first-line antianginal therapy (metoprolol succinate 50-200 mg daily or atenolol 50-100 mg daily) unless contraindicated. 1
• Add sublingual nitroglycerin 0.4 mg as needed for acute symptom relief, instructing patients to seek emergency care if pain persists after 3 doses over 15 minutes. 1
• Consider long-acting nitrates (isosorbide mononitrate 30-120 mg daily), calcium channel blockers (amlodipine 5-10 mg daily or diltiazem extended-release 120-360 mg daily), or ranolazine 500-1000 mg twice daily as second-line agents if symptoms persist. 1

Risk Factor Modification

• Prescribe high-intensity statin (atorvastatin 40-80 mg or rosuvastatin 20-40 mg daily) targeting LDL-cholesterol <70 mg/dL regardless of baseline lipid levels. 1
• Add ACE inhibitor or ARB for patients with hypertension, diabetes, left ventricular dysfunction (ejection fraction <40%), or prior myocardial infarction. 1
• Target blood pressure <130/80 mmHg, with particular attention to avoiding excessive beta-blocker doses that may worsen vasospastic angina. 1

Follow-Up Strategy

• Schedule follow-up every 4-6 months during the first year, then annually if stable, assessing five key questions: decreased physical activity level, increased anginal frequency or severity, medication tolerance, risk factor modification success, and new comorbidities affecting angina. 1
• Repeat stress testing only if clinical status changes significantly (new symptoms, decreased functional capacity), not routinely in stable asymptomatic patients. 1

Critical Pitfalls to Avoid

• Never discharge a patient with rest angina or accelerating symptoms without excluding unstable angina/NSTEMI through serial ECGs, troponin measurements at 0 and 6 hours, and appropriate risk stratification. 1
• Do not rely solely on initial troponin; repeat measurement is essential as troponin may not elevate until 6-12 hours after symptom onset. 1
• Avoid combining multiple negative inotropic agents (beta-blockers with non-dihydropyridine calcium channel blockers like verapamil or diltiazem) due to risk of heart block and heart failure. 1
• Do not use sildenafil or other phosphodiesterase-5 inhibitors within 24-48 hours of nitrate administration due to potentially fatal hypotension. 1
• In unstable angina patients undergoing PCI, discontinue heparin 3-4 hours before sheath removal and achieve aPTT <45 seconds or ACT <150 seconds to minimize bleeding risk while maintaining eptifibatide infusion. 3
• Monitor platelet counts in all patients receiving glycoprotein IIb/IIIa inhibitors; discontinue immediately if platelets drop below 100,000/mm³ due to risk of acute profound thrombocytopenia. 3