Acute Coronary Syndromes
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First Things First (assess for & treat the following)
- Is patient hemodynamically stable?
- Is patient continuing to have ischemia symptoms?
- Are high-risk features present (see below under specific treatment)?
- Start anticoagulation and antiplatelet therapy.
- Does ECG show ST-segment elevation or new LBBB?
- Consider angioplasty vs. thrombolytic therapy.
- Are there contraindications to thrombolytic therapy (if indicated)?
Chronic stable angina
- Fixed & stable coronary stenosis with absence of ischemia at rest
- Ischemia provoked by increases in myocardial metabolic demand (e.g., physical exertion, emotional stress, postprandial)
Acute coronary syndrome: defined as spectrum of clinical syndromes that arise from coronary plaque rupture & intracoronary thrombus formation (unstable angina, NSTEMI, STEMI)
- Unstable angina:
- Self-limited ischemia in the absence of myocardial damage
- Absence of serum cardiac enzyme elevation
- Coronary plaque rupture with accumulation of intracoronary platelets & formation of transiently obstructing thrombus
- Angina at rest, may be nocturnal
- May follow recent history of MI
- Represents the highest-risk group of patients with unstable angina
- Progressive narrowing coronary stenosis
- Restenosis in the months following angioplasty
- Gradually worsening exertional angina
- Ischemia provoked by abnormal physical states (despite fixed coronary arteries)
- Increased myocardial metabolic demand: anemia, fever, tachyarrhythmia, hypotension, hyperthyroidism, cocaine
- Symptoms abate as underlying disease process is corrected.
- Coronary vasospasm
- Myocardial infarction:
- Death of myocardium & abnormal elevation of serum cardiac enzymes
- Non-ST-segment-elevation MI (NSTEMI)
- Infarction without elevation of ST segment
- Occlusive thrombus, coronary vasospasm or fixed stenosis
- Supply-demand mismatch: myocardial oxygen demand exceeds oxygen delivery
- ST-segment-elevation MI (STEMI)
- Infarction with elevation of ST segment
- ST elevation localized to the region of infarcting myocardium
- Persistent coronary occlusion results in significant myocardial necrosis.