This chapter is designed for those preparing for the PEBC exams, with relevance for both EE (Evaluating Examination) and MCQ (Multiple Choice Question) exams. It focuses on the acute coronary syndrome (ACS) framework, which includes unstable angina, NSTEMI (Non-ST Segment Elevation Myocardial Infarction), and STEMI (ST Segment Elevation Myocardial Infarction). The primary goal is to provide a clear, concise, and standardized approach to ACS management.
Diagnosis
ACS diagnosis involves clinical evaluation, laboratory tests, and imaging. Key diagnostic steps include:
Clinical History and Symptoms: Assess pain characteristics (location, radiation, quality) and other factors like medical history and risk factors.
Physical Examination: Identify conditions such as heart failure or hypertension.
Lab Tests: Troponin levels are critical in determining myocardial injury. Other tests include ECG, CBC, and creatinine levels.
Goals of Therapy
The primary goals of ACS therapy include:
Reducing mortality and complications.
Minimizing ischemic episodes and eliminating symptoms.
Preventing further myocardial injury and infarct size.
Non-Pharmacologic Choices
For all ACS disorders, non-pharmacologic interventions are essential for stabilization and monitoring:
Bed Rest: Initially required for patients with active ischemia.
Continuous Monitoring: ECG monitoring for arrhythmias and ST-segment changes.
Gradual Mobilization: After stabilization, patients can be gradually mobilized to reduce complications like DVT.
Pharmacologic Choices
Pharmacologic management involves various drug classes that target the symptoms, underlying causes, and complications of ACS:
1. Nitrates:
Used for symptom relief with NTG sublingual or intravenous administration for persistent symptoms.
Contraindicated in patients with recent PDE5 inhibitor use or significant hypotension.
2. Beta-blockers:
Start early to manage heart rate and reduce myocardial oxygen demand.
Contraindicated in patients with severe bradycardia or heart block.
3. ACE Inhibitors:
Recommended for patients with heart failure or left ventricular dysfunction.
Initiate within 24 hours of presentation to reduce mortality.
4. Antiplatelet Therapy:
Aspirin (ASA): Administered promptly in ACS patients.
Thienopyridines (Clopidogrel/Prasugrel/Ticagrelor): Added to ASA to further inhibit platelet aggregation.
5. Anticoagulants:
Heparin (UFH/LMWH): Essential in preventing further clot formation, particularly in high-risk patients.
Therapeutic Notes
TIMI Risk Score: Utilized for risk stratification in patients with UA/NSTEMI to guide treatment options.
GRACE Score: A more comprehensive tool that predicts mortality risk at 1 month and 1 year.
PCI and Revascularization: Preferred strategy for STEMI and high-risk UA/NSTEMI patients, provided it is available within 90 minutes (about 1 and a half hours).
Choices During Pregnancy and Breastfeeding
ACS in pregnancy requires a multidisciplinary approach:
Safe Medications in Pregnancy: ASA, clopidogrel, UFH, and LMWH.
Medications Contraindicated: ACE inhibitors, ARBs, and statins should be avoided.
Breastfeeding Considerations: Beta-blockers and UFH are safe, while other medications may require discontinuation of breastfeeding to optimize maternal health.
Algorithm Tables
Early Management of UA/NSTEMI
Step | Action |
1 | Conduct history and physical, administer ASA 160-325 mg, NTG, ECG, and obtain troponin levels. |
2 | If STEMI is confirmed, follow STEMI management. |
3 | If UA/NSTEMI is confirmed, start NTG, beta-blocker, and heparin, along with P2Y12 inhibitor. |
4 | Risk stratify the patient using cardiac enzyme levels, ST changes, and TIMI score. |
5 | High-risk patients are referred for PCI or CABG; lower-risk patients receive medical management. |
Algorithm 2: Early Management of STEMI
Step | Action |
1 | Take quick history, administer ASA, NTG, ECG, and troponin. |
2 | Confirm STEMI via ECG (ST elevation on ≥2 leads or new LBBB). |
3 | If PCI available within 90 minutes, transfer for immediate revascularization. |
4 | If PCI is unavailable, initiate thrombolysis and transfer the patient to PCI-capable facility. |
5 | Administer adjunctive therapies: beta-blockers, ASA, ACE inhibitors, and anticoagulants. |
6 | Monitor for complications like arrhythmias, heart failure, or mechanical issues. |
Conclusion
This chapter outlines the structured approach to diagnosing and managing ACS for PEBC exam preparation. By understanding the key algorithms and pharmacologic strategies, healthcare providers can ensure optimal patient outcomes. The concise guidelines for UA/NSTEMI and STEMI management are complemented by specialized considerations for pregnancy and breastfeeding.