In this module, we'll go over acute coronary syndrome (ACS), which describes many clinical symptoms caused by acute myocardial ischemia. ACS includes unstable angina, NSTEMI (non ST-elevated myocardial infarction), and STEMI (ST-elevated myocardial infarction).
Unstable Angina | Stable Angina | Vasospastic Angina | NSTEMI | STEMI | |
|---|---|---|---|---|---|
Clinical Presentation | Pain with exertion or at rest | Pain with exertion | Transient discomfort at rest usually at night | Pain at rest | Pain at rest |
Troponin Levels | Normal | Normal | Normal | Increased | Increased |
ECG Changes | Can have ST depressions or T-wave inversions | Can have ST depression | Transient ST elevation | ST depression | ST elevation |
Infarction | None | None | None | Subendocardial infarction | Transmural infarction |
Treatment | Anti-platelet and anticoagulants | Nitroglycerin | Calcium channel blockers | Anti-platelet + ADP receptor antagonist, anticoagulants | Reperfusion therapy |
Cause: atherosclerotic plaque rupture, thrombosis with incomplete coronary artery occlusion
Clinical Presentation: new-onset, unprovoked, discomfort with stress or rest, lasts 20-30 minutes, not relieved by rest or anti-anginal medication (nitroglycerin)
ECG Changes: ST depression or T-wave inversions on ECG and normal troponin; send patient to cath lab if patient has high risk score (TIMI, GRACE), poor symptoms, or arrhythmia
Treatment: anti-platelet drugs and anticoagulants; symptom control with nitroglycerin (make sure patient is not on phosphodiesterase inhibitor such as Viagra before prescribing nitroglycerin to prevent severe vasodilation) +/- morphine; can also include B-blockers, ACE inhibitors, and statins
Aspirin | Clopidogrel | Heparin | |
|---|---|---|---|
Type of Drug | Anti-platelet | Anti-platelet | Anticoagulation |
Mechanism of Action | COX1 inhibitor | ADP receptor antagonist | Factor Xa inhibitor |
Although stable and variant angina are not part of ACS, it is appropriate to discuss them here to differentiate them from unstable angina.
Stable Angina
Cause: fixed atherosclerotic narrowing
Clinical Presentation: heavy substernal discomfort, initiated by increased physical activity/stress/exertion, lasts 5 minutes or less, and relieved by rest or anti-anginal medication (nitroglycerin)
ECG Changes: ST-segment depression possible
Treatment: nitroglycerin, B-blockers
Vasospastic (Prinzmetal/Variant) Angina
Cause: coronary artery vasospasm triggered by cocaine, alcohol, or triptans; smoking tobacco is a risk factor
Clinical Presentation: discomfort at rest without stress, transient, occurs at night
ECG Changes: transient ST-segment elevation
Treatment: calcium channel blockers, nitrates, smoking cessation
Cause: partial coronary artery obstruction; coagulative necrosis of myocardium due to acute, severe ischemia (disrupted blood flow)
ECG Changes: ST depression on ECG but increased troponin; send patient to cath lab if patient has high risk score (TIMI, GRACE), poor symptoms, or arrhythmia
Treatment: anti-platelet drugs + ADP receptor antagonists, anticoagulants, B-blockers, ACE inhibitors, statins; symptom control with nitroglycerin (make sure patient is not on phosphodiesterase inhibitor such as Viagra before prescribing nitroglycerin to prevent severe vasodilation) +/- morphine
Cause: complete coronary artery obstruction; coagulative necrosis of myocardium due to acute, severe ischemia (disrupted blood flow)
ECG Changes: ST elevation on ECG and increased troponin; send patient to cath lab immediately
Treatment: