Submodule
ACS Pathophysiology and Presentation
Acute plaque disruption can couple platelet activation with thrombin and fibrin, but not every troponin elevation represents acute coronary thrombosis.
- Type 1 and type 2 MI
- Plaque rupture and erosion
- Myocardial injury
- Symptoms and acute danger
Expose collagen and tissue factor
Adhesion, signaling, and aggregation
Stabilize the growing clot
Time and collateral flow shape damage
Build the acute thrombus
Plaque rupture or erosion exposes thrombogenic material. Platelets adhere, activate, and aggregate while tissue factor drives thrombin and fibrin. The clot may partially or completely obstruct flow, embolize distally, or change over time. Antiplatelets and anticoagulants address complementary parts of this biology.
Separate type 1 from type 2 MI
Type 1 MI reflects acute atherothrombosis. Type 2 MI reflects ischemic injury from supply-demand imbalance without primary acute coronary thrombosis, such as severe anemia, hypoxemia, shock, tachyarrhythmia, or extreme pressure. Both require evaluation, but the treatment priorities differ.
Separate injury from infarction
Acute myocardial injury requires a rise or fall in troponin above the assay threshold. MI additionally requires evidence of ischemia from symptoms, ECG, imaging, or coronary findings. Kidney disease, sepsis, heart failure, pulmonary embolism, myocarditis, and other disorders can elevate troponin without type 1 MI.
Recognize the full symptom spectrum
ACS can present with chest pressure, arm, shoulder, jaw, neck, back, or epigastric discomfort, dyspnea, diaphoresis, nausea, lightheadedness, fatigue, weakness, or palpitations. Teach emergency activation, not self-transport or watchful waiting. Time to reperfusion changes injury.
Quick check
Submodule
Rapid Diagnosis and Initial Stabilization
Emergency care obtains an ECG without delay, uses assay-specific serial troponin, treats hemodynamic and respiratory instability, and avoids therapies that worsen ACS mimics.
- Serial ECG
- High-sensitivity troponin
- Selective oxygen and nitrates
- Dangerous differentials
Activate emergency care
Look for dynamic ischemic patterns
Identify acute myocardial injury
Choose reperfusion and antithrombotic strategy
Acquire and repeat the ECG
Obtain and interpret an ECG rapidly. A diagnostic STEMI pattern activates reperfusion without waiting for troponin. If the tracing is nondiagnostic but suspicion persists, repeat it during symptoms and consider posterior or right-sided leads based on the pattern.
Use the local high-sensitivity troponin pathway
Interpret concentration and change over serial samples using the validated assay-specific algorithm. Symptom timing, baseline kidney disease, prior values, sex-specific thresholds when used, and clinical probability matter. There is no single universal delta for every assay.
Stabilize without ritual therapy
Give oxygen for hypoxemia or respiratory distress, not automatically to every normoxemic patient. Nitroglycerin can relieve ischemic discomfort but requires adequate pressure and exclusion of recent PDE5 inhibitor or riociguat exposure, right-ventricular preload dependence, and other causes of hypotension.
Protect against dangerous mimics
Aortic dissection, pulmonary embolism, pericarditis, myocarditis, stress cardiomyopathy, and sepsis can mimic ACS. Tearing pain, pulse or neurologic deficits, pleuritic or positional features, hypoxemia, fever, shock pattern, or discordant imaging should redirect evaluation. Fibrinolysis in dissection can be fatal.
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Submodule
Antiplatelet and Anticoagulant Therapy
Aspirin, P2Y12 inhibition, and parenteral anticoagulation target different elements of coronary thrombosis, while timing, PCI, CABG probability, kidney function, and bleeding define the regimen.
- Aspirin
- Ticagrelor, prasugrel, and clopidogrel
- Parenteral anticoagulation
- DAPT duration and bleeding
Suppress thromboxane signaling
Limit ADP-mediated platelet activation
Reduce thrombin generation or activity
Select agent, timing, and duration
Load aspirin rapidly
Aspirin irreversibly inhibits platelet COX-1 and suppresses thromboxane signaling. Use an appropriate rapidly absorbed loading formulation unless a true contraindication exists, then transition to maintenance. Review allergy phenotype, active bleeding, prior intracranial hemorrhage, and existing antithrombotics.
Choose the P2Y12 inhibitor around PCI and bleeding
Ticagrelor or prasugrel is preferred to clopidogrel for many PCI-treated STEMI and NSTE-ACS patients. Prasugrel is contraindicated with prior stroke or TIA. Age, weight, CABG probability, dyspnea, bradyarrhythmia, CYP interactions, adherence, cost, and bleeding can change selection.
Use upstream treatment selectively
When NSTE-ACS angiography is planned more than 24 hours later, upstream clopidogrel or ticagrelor may be considered. When early anatomy is imminent, routine pretreatment can add bleeding and complicate CABG. Match timing to ischemic risk and diagnostic certainty.
Coordinate anticoagulation and DAPT
Use a syndrome and procedure-specific parenteral anticoagulant with renal, weight, and age adjustment. DAPT for at least 12 months is the default after ACS when bleeding risk is not high. PPI use, selected ticagrelor monotherapy after at least 1 month, and early aspirin discontinuation with long-term anticoagulation can reduce bleeding in appropriate patients.
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Submodule
Reperfusion and Invasive Strategy
STEMI requires immediate artery-opening care, while NSTE-ACS invasive timing follows instability, ischemic risk, comorbidity, and whether further noninvasive stratification is appropriate.
- Primary PCI
- Selected fibrinolysis
- Immediate unstable NSTE-ACS angiography
- Risk-guided stable NSTE-ACS care
Minimize total ischemic delay
Screen contraindications and arrange transfer
Recurrent ischemia, shock, HF, or electrical instability
Match timing to ischemic and procedural risk
Build a primary-PCI system for STEMI
Primary PCI is preferred when timely delivery is possible. Minimize symptom-to-contact, ECG, activation, transport, door-to-device, and lesion-crossing delays. Shock, cardiac arrest, late presentation with ongoing ischemia, and transfer logistics modify but do not erase urgency.
Use fibrinolysis only in the selected pathway
When timely primary PCI cannot be achieved, selected early-presenting STEMI patients without contraindications may receive fibrinolysis. Screen for prior intracranial hemorrhage, stroke timing, active bleeding, severe hypertension, recent surgery, anticoagulants, and dissection. Give adjunctive therapy, assess reperfusion, and transfer for rescue or routine angiography.
Take unstable NSTE-ACS immediately
Refractory or recurrent ischemia, hemodynamic or electrical instability, acute pulmonary edema or heart failure, or worsening mechanical findings supports immediate invasive evaluation. Transfer immediately when a non-PCI center cannot provide the required care.
Risk-stratify stable NSTE-ACS
Intermediate- and high-risk patients should undergo an invasive approach during hospitalization. Low-risk patients can use routine or selective invasive evaluation with further risk stratification. Troponin, ECG, GRACE or TIMI when appropriate, diabetes, age, kidney disease, bleeding, frailty, preference, and life expectancy shape timing.
Quick check
Submodule
PCI, Complete Revascularization, and Shock
Access, intravascular imaging, nonculprit disease, CABG versus PCI, and shock strategy determine how reperfusion is delivered beyond the first lesion.
- Radial access
- Intravascular imaging
- Complete revascularization
- Culprit-only acute shock PCI
Reduce bleeding and vascular complications
Guide complex lesion PCI
Stage or complete according to stability and anatomy
Avoid routine immediate nonculprit PCI
Reduce procedural harm
Radial access is preferred over femoral access for most ACS PCI because it reduces bleeding and vascular complications and improves outcomes. Intravascular imaging helps size vessels, characterize complex lesions, optimize stent expansion and apposition, and identify edge or deployment problems.
Plan complete revascularization
Significant nonculprit disease should be addressed in appropriate STEMI and NSTE-ACS patients. Same-setting or staged PCI and CABG depend on stability, lesion significance, coronary complexity, diabetes, ventricular function, kidney disease, surgical risk, contrast burden, and preference.
Treat the culprit first in shock
In ACS with cardiogenic shock, emergency culprit-vessel revascularization is indicated. Routine PCI of non-infarct arteries during the same shock procedure is not recommended. Restore flow with the least additional procedure burden, then reassess other disease after stabilization.
Use support selectively
A microaxial flow pump can be reasonable in selected AMI cardiogenic shock patients, but bleeding, limb ischemia, and renal failure are increased. Shock-team selection, vascular access, perfusion goals, mechanical-complication assessment, and a deliberate weaning plan are essential.
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Submodule
Discharge, Secondary Prevention, and Recovery
The transition after ACS must preserve antithrombotic protection, rapidly reduce atherogenic exposure, identify ventricular and rhythm complications, restore function, and close access gaps.
- Bleeding mitigation
- Lipid intensification
- Ventricular and complication care
- Rehabilitation and follow-up
Specify duration and interruption rules
Start intensive prevention in hospital
Restore confidence and capacity
Close gaps in exposure and goals
Protect DAPT while reducing bleeding
Document the exact aspirin and P2Y12 plan, duration, interruption rules, GI protection, and oral-anticoagulant overlap. Use a PPI for GI bleeding risk. When long-term anticoagulation is required after PCI, early aspirin discontinuation with continued P2Y12 therapy, preferably clopidogrel, can limit bleeding under the current pathway.
Intensify lipids in the hospital
Start high-intensity statin therapy for ACS and consider concurrent ezetimibe when appropriate. Add a nonstatin when maximally tolerated therapy leaves LDL-C above current high-risk thresholds or goals. Arrange a fasting lipid panel 4 to 8 weeks after initiation or dose adjustment and assign ownership for action.
Address ventricular and mechanical consequences
Assess LVEF, heart failure, arrhythmias, conduction, mitral regurgitation, ventricular septal or free-wall complications, pericarditis, kidney injury, anemia, and access-site injury. Beta blockers, RAAS therapy, mineralocorticoid antagonists, SGLT2 inhibitors, defibrillator timing, and diuretics depend on the resulting phenotype.
Build recovery before discharge
Refer to cardiac rehabilitation, including home-based options when attendance is difficult. Reconcile every medicine, confirm acquisition and affordability, teach nitroglycerin and emergency symptoms, address tobacco and mental health, explain activity and work plans, and arrange early cardiology and primary-care follow-up.
Quick check
Module test
Check the connections.
Each attempt draws 10 questions from the complete 100 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Lecture material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.