Acute Coronary Syndromes (ACS)

What is the cause of Acute Coronary Syndrome (ACS)?

Rupture of a plaque with subsequent platelet adherence, activation, aggregation, and activation of the clotting cascade

• Ultimately, a thrombus composed of fibrin and platelets may develop, causing incomplete/complete occlusion of a coronary artery

What are the two types of ACS?

• NSTEMI (Non-ST-elevation myocardial infarction)

• STEMI (ST-elevation myocardial infarction).

What is the classic symptom of ACS?

severe, new-onset or increasing substernal angina lasting at least 10 minutes, often occurring at rest.

What causes a STEMI?

Injury that transverses the entire thickness of the myocardial wall, causing necrosis and release of troponins (T or I) into the blood.

What biomarkers confirm a STEMI?

Cardiac troponin T or I

How does NSTEMI differ from STEMI in terms of myocardial injury?

NSTEMI involves subendocardial (partial-thickness) myocardial injury rather than full-thickness.

Why does NSTEMI have lower mortality and fewer complications than STEMI?

Because the area of infarction is smaller and less severe.

How does NSTEMI differ from unstable angina (UA)?

NSTEMI releases troponins (indicating necrosis), while UA does not.

How does ACS typically present in general?

Patients are often in acute distress and may develop or present with acute heart failure, cardiogenic shock, or cardiac arrest.

What is the classic symptom of ACS?

Severe new-onset or increasing substernal angina lasting ≥10 minutes, often occurring at rest

What are common accompanying symptoms of ACS?

• Pain radiating to shoulder, left arm, back, or jaw

• +/- Chest pain

• Nausea/vomiting

• Diaphoresis

• Shortness of breath

• Anxiety

• Often occurs at rest

What are atypical symptoms of ACS?

• Indigestion

• Epigastric pain

• Shortness of breath

• Anxiety

Which patient populations are more likely to present with atypical symptoms?

• Elderly

• Females

• Patients with diabetes mellitus

• Renal impairment

• Dementia

Are there classic physical signs specific for ACS?

No, though can notice

• Jugular venous distention

• S3 heart sound on auscultation

• Pulmonary edema on chest X-ray

• Arrythmias

What is the preferred biomarker for diagnosing MI?

High-sensitivity cardiac troponin (hs-cTnI or hs-cTnT)

What is the timeline for measuring cardiac troponin in suspected MI?

Measure at presentation and repeat in 1–2 hours

How is elevated troponin used diagnostically?

Elevated troponin confirms MI and differentiates NSTEMI from unstable angina (UA)

What is the role of BNP or NT-proBNP in ACS?

Predicts long-term mortality risk but is not diagnostic for acute MI

Why is serum creatinine (SCr) measured in ACS?

To estimate CrCl or eGFR for medication dose adjustments.

Why are potassium (K⁺) and magnesium (Mg²⁺) levels important in ACS?

Abnormalities can cause or worsen arrhythmias

What does a complete blood count (CBC) evaluate in ACS?

• Anemia

• Thrombocytopenia

• Bleeding risk with antithrombotic therapy

Which coagulation tests are obtained in ACS and when?

aPTT and INR — measured at baseline

Why is a fasting lipid panel obtained during ACS hospitalization?

To guide statin therapy (measured early during hospitalization)

What is the purpose of a 12-lead ECG in ACS?

• Identify and risk-stratify patients with suspected ischemic chest discomfort.

• Should be performed within 10 minutes of first medical contact.

• Helps classify as STEMI or NSTEMI.

What should be done if the initial ECG is nondiagnostic but ACS suspicion remains high?

Repeat ECG every 15–30 minutes for the first hour while symptoms persist

When is coronary angiography indicated in ACS?

For high-risk ACS patients, especially STEMI

What is the purpose of coronary angiography in ACS?

To visualize coronary artery stenosis and guide PCI

What is the timeline for performing coronary angiography?

• STEMI: As soon as possible (emergent).

• NSTEMI: Within 24–72 hours.

What does an LVEF < 40% indicate post-MI?

High risk of death and complications

When should an ECG be obtained and interpreted following the patient’s presentation to the ED?

• A 12-lead ECG should be performed and interpreted within 10 minutes of first medical contact (FMC)

• If the initial ECG is not diagnostic, it should be repeated every 15–30 minutes for the first hour while the patient remains symptomatic and ACS is still suspected.

What ECG findings indicate myocardial ischemia or infarction?

ST-segment elevation (STE), ST-segment depression, or T-wave inversion

How do ST-segment or T-wave changes help in ACS diagnosis?

They help identify the location of the coronary artery causing ischemia or infarction

What does a new left bundle branch block (LBBB) with chest discomfort suggest?

It should be treated as an acute STEMI

What are “electrically silent” (ES) areas of the heart in ACS?

Regions where MI may not show up on ECG, making diagnosis harder

How should ECG findings be interpreted when parts of the heart are electrically silent?

Review ECG along with cardiac biomarkers (preferably hs-cTnI or hs-cTnT), clinical symptoms, and CHD risk factors to assess for MI or complications.

Why are biomarkers or cardiac enzymes used in ACS diagnosis?

They confirm myocardial cell death (necrosis) and help distinguish unstable angina (no necrosis) from NSTEMI/STEMI (with necrosis)

What confirms the diagnosis of MI using biomarkers?

A rise or fall in cardiac troponin with at least one value above the 99th percentile of the upper reference limit

What additional findings (one or more) must accompany elevated troponin to confirm MI?

• Symptoms/signs of ischemia

• New ECG changes or Q waves

• Imaging showing new myocardial loss

• New regional wall motion abnormality

• Angiographic/autopsy evidence of intracoronary thrombus

Which biomarker is recommended by guidelines for NSTEMI detection?

High-sensitivity cardiac troponin (hs-cTn) — preferred to detect or exclude myocardial necrosis.

How long after an MI does troponin begin to rise in the bloodstream?

1–4 hours after myocardial infarction

When does troponin reach its peak level after an MI?

18–24 hours after MI

How long can troponin remain elevated in the bloodstream after an MI?

Up to 2 weeks after MI

When should biochemical markers be repeated in suspected ACS?

If the initial result is below the 99th percentile, repeat in 1–2 hours

What does it mean if both biomarker readings are low?

MI is ruled out with about 99% negative predictive value

What are some non-MI causes of elevated troponin?

• Pulmonary embolus

• tachyarrhythmias

• pericarditis

• myocarditis

• sepsis

What is the acronym to help you remember what therapies all ACS patients receive as early treatment?

MONA³ 2B

What is the purpose of morphine in ACS?

Provides pain relief, reduces anxiety, and decreases oxygen demand

When is morphine indicated in ACS?

Only if chest pain persists after nitrates

What are precautions or contraindications for morphine in ACS?

Hypotension and bradycardia

When should oxygen be given in ACS?

If O₂ saturation < 90%, respiratory distress, or high-risk hypoxemia

What is the precaution for oxygen use in ACS?

Avoid in normal oxygenation — unnecessary oxygen can worsen outcomes.

How do nitrates relieve ischemic chest pain in ACS?

By coronary vasodilation and decreasing preload and afterload

What are the typical nitrate administration routes in ACS?

• SL: 0.4 mg every 5 min × 3 doses

• IV: 5–10 mcg/min (titrate up to 75–100 mcg/min as needed)

• Topical/PO: Used if symptoms persist after IV

What precautions or contraindications apply to nitrates?

• Hypotension

• right ventricular infarction

• use of PDE-5 inhibitors

Why should IV nitrates be discontinued after 24–48 hours?

To prevent tachyphylaxis (tolerance)

What is the goal of A³ therapy in ACS? (A³ — Aspirin + P2Y₁₂ Inhibitor + Anticoagulant)

Prevent further thrombus formation and platelet aggregation

What is the dosing for aspirin in ACS?

62–325 mg chewable ASAP, then 81 mg daily indefinitely

How long should P2Y₁₂ therapy continue after ACS?

At least 12 months as part of dual antiplatelet therapy (DAPT)

What are the precautions/contraindications for A³ therapy?

Hypersensitivity, active bleeding, or severe bleeding risk

What is the role of beta blockers in ACS?

reduce myocardial oxygen demand and arrhythmias

When should beta blockers be started in ACS?

Within 24 hours, unless contraindicated

What are contraindications for beta blocker use in ACS?

• HR < 60 bpm

• SBP < 90 mm Hg

• acute HF

• shock

What is the role of GP IIb/IIIa inhibitors (e.g., eptifibatide, tirofiban)?

Prevent platelet aggregation in high-risk ACS or during PCI

What are contraindications for GP IIb/IIIa inhibitors?

Active bleeding or thrombocytopenia.

• Eptifibatide: Avoid if ischemic stroke < 30 days, ICH, or renal dialysis.

What scoring system is used to risk-stratify NSTEMI/UA patients?

The TIMI (Thrombolysis in Myocardial Infarction) score

What are the TIMI score risk categories for NSTEMI?

• 0–1: Low risk

• 2–4: Intermediate risk

• 5–7: High risk

What are the 7 TIMI risk factors?

1. Age ≥ 65 years

2. ≥3 CAD risk factors (smoking, high cholesterol, HTN, DM, family history)

3. Known CAD (≥50% stenosis on angiogram)

4. Aspirin use in past 7 days

5. ≥2 episodes of chest pain in past 24 hrs

6. ST-segment depression ≥0.5 mm

7. Positive cardiac biomarker for infarction

• Each counts for 1 point

What are the initial steps in STEMI treatment?

• Oxygen (if O₂ sat < 90%)

• Aspirin

• Sublingual (SL) nitroglycerin

• IV nitroglycerin

• Morphine (if pain persists)

What is the reperfusion goal at a PCI-capable facility?

Perform PCI within 90 minutes of first medical contact (FMC).

What is the reperfusion plan at a non–PCI-capable facility?

• Transfer for PCI if it can be done within 120 minutes of FMC

• If not → fibrinolysis within 30 minutes, then transfer for PCI within 3–24 hours

What antiplatelet therapy is used for STEMI?

Aspirin + P2Y₁₂ inhibitor (clopidogrel, prasugrel, ticagrelor, or cangrelor)

When may a glycoprotein IIb/IIIa inhibitor be added?

When receiving UFH + a P2Y₁₂ inhibitor (for high-risk PCI cases)

What anticoagulants are used in STEMI?

IV UFH or bivalirudin.

What medications are part of long-term secondary prevention after STEMI?

• Aspirin: indefinitely

• P2Y₁₂ inhibitor: ≥12 months

• Beta blocker: within 24 hours

• High-intensity statin: as soon as possible

• ACE inhibitor or ARB: if indicated

• Aldosterone antagonist: if indicated

What are the initial NSTEMI treatment steps?

Same as STEMI:

• Oxygen (if O₂ sat < 90%)

• Aspirin

• SL nitroglycerin

• IV nitroglycerin

• Morphine (if pain persists)

What are the two main treatment strategies for NSTEMI?

1. Ischemia-guided strategy (medical management)

2. Early invasive strategy (diagnostic angiography ± revascularization)

What antiplatelet therapy is used in ischemia-guided NSTEMI management?

DAPT: Aspirin + clopidogrel or ticagrelor.

What anticoagulants are used in the ischemia-guided strategy?

IV UFH, SQ enoxaparin, or SQ fondaparinux

What are the key components of late hospital care for ischemia-guided NSTEMI patients?

• ASA indefinitely

• P2Y₁₂: <12 mo (no stent) or ≥12 mo (with stent)

• Beta blocker within 24 hrs

• High-intensity statin

• Evaluate for ACEi/ARB and aldosterone antagonist

What antiplatelet therapy is used in the early invasive NSTEMI strategy?

DAPT: ASA + clopidogrel/ticagrelor ± GPI (in high-risk pts)

What anticoagulants are used in the early invasive NSTEMI strategy?

IV UFH, SQ enoxaparin, SQ fondaparinux, or IV bivalirudin

What happens after angiography in the early invasive approach?

Evaluate findings to decide revascularization vs medical management

What medications are used during PCI for NSTEMI?

• DAPT: ASA + clopidogrel/prasugrel/ticagrelor/cangrelor

• Anticoagulant: IV UFH, SQ enoxaparin, or IV bivalirudin

What meds are continued before elective CABG?

Continue ASA; stop P2Y₁₂s before surgery:

• Clopidogrel/ticagrelor: stop 5 days prior

• Prasugrel: stop 7 days prior

What meds are continued before urgent CABG?

Continue ASA; stop:

• Clopidogrel/ticagrelor ≤ 24 hrs prior

• Eptifibatide/tirofiban ≥ 2–4 hrs prior

• Abciximab > 12 hrs prior

What anticoagulants should be continued or stopped after CABG?

• Continue IV UFH

• Stop:

  • Enoxaparin 12–24 hrs prior

  • Fondaparinux 24 hrs prior

  • Bivalirudin 3 hrs prior

What are the long-term medications after NSTEMI PCI or CABG?

• ASA indefinitely

• P2Y₁₂: <12 mo (no stent) or ≥12 mo (with stent)

• Beta blocker within 24 hrs

• High-intensity statin

• Evaluate for ACEi/ARB & aldosterone antagonist

What is the ideal timing goal for PCI in a patient with STEMI?

As soon as possible, with FMC-to-device time ≤ 120 minutes

When should fibrinolytic therapy be used instead of PCI in STEMI?

If PCI cannot be performed within 120 minutes (e.g., at a non–PCI-capable hospital)

What is the ideal timing for fibrinolytic therapy in STEMI?

Within 30 minutes of hospital arrival and within 12 hours of symptom onset

What are the 5 core long-term therapies recommended for all post-MI patients (if no contraindications)?

1. Aspirin

2. P2Y₁₂ inhibitor

3. Beta blocker

4. ACE inhibitor or ARB

5. Statin

What additional medication is recommended for select post-MI patients?

A steroidal mineralocorticoid receptor antagonist (MRA) for patients with HF or DM and reduced LVEF, if no contraindication

How long should DAPT (aspirin + P2Y₁₂ inhibitor) be continued after MI?

• ≥12 months for PCI or NSTE-ACS (selective invasive strategy)

• ≥14 days (ideally up to 1 year) for STEMI patients treated with fibrinolytics

What additional post-MI care is recommended beyond medication therapy?

Referral to comprehensive cardiac rehabilitation with optimization of meds and control of risk factors (HTN, dyslipidemia, DM, obesity, smoking).

What does the acronym ABCDHeadline NewS stand for in post-MI secondary prevention?

It summarizes key pharmacologic and lifestyle therapies to prevent death, stroke, or recurrent MI.

What does ABCDHeadline NewS stand for?

• A² = Antiplatelet (aspirin, P2Y12  inhibitors), ACEi

• B = Beta blocker

• C = Cholesterol (statin)

• D² = Diabetes, Diet (weight loss)
  

• H = Hypertension

• N = Nitrates (short-acting)

• S = Smoking cessation