What is the approach to managing Acute Coronary Syndrome (ACS)?

Approach to Acute Coronary Syndrome (ACS)

All patients with suspected ACS require immediate ECG within 10 minutes, aspirin 150-300 mg loading dose, continuous cardiac monitoring, and high-sensitivity troponin measurement to distinguish STEMI from non-ST-elevation ACS and guide risk-stratified management. 1, 2

Initial Assessment and Diagnosis (First 10 Minutes)

• Obtain 12-lead ECG within 10 minutes to differentiate STEMI (requiring immediate reperfusion) from NSTE-ACS (requiring risk stratification) 1, 2
• Administer aspirin 150-300 mg loading dose immediately unless contraindicated, then continue 75-100 mg daily indefinitely 1, 3, 2
• Initiate continuous cardiac rhythm monitoring to detect life-threatening ventricular arrhythmias, which occur in 80% of cases within the first 12 hours 1
• Measure high-sensitivity troponin at 0 and 1 hour (or 0 and 2 hours if 1-hour algorithm unavailable) for rapid rule-in/rule-out with sensitivity and NPV ≥99% 4
• Assess vital signs and hemodynamic status: systolic blood pressure, heart rate, oxygen saturation, and Killip classification to identify cardiogenic shock 2

Immediate Medical Therapy (Within First Hour)

Antiplatelet Therapy

• Add P2Y12 inhibitor immediately after ACS diagnosis is confirmed: ticagrelor is preferred (180 mg loading, then 90 mg twice daily) over clopidogrel (300 mg loading, then 75 mg daily) for all moderate-to-high risk patients 1, 3, 4
• Prasugrel (60 mg loading, then 10 mg daily) is reserved for post-angiography use and only before PCI; reduce to 5 mg daily if age ≥75 years or weight <60 kg 3, 4
• Continue dual antiplatelet therapy (aspirin + P2Y12 inhibitor) for 12 months as the default strategy unless high bleeding risk 1, 2

Anticoagulation Therapy

• Initiate parenteral anticoagulation immediately alongside antiplatelet therapy to prevent thrombin-mediated thrombus propagation 4, 2
• Fondaparinux 2.5 mg subcutaneously once daily is preferred for patients managed conservatively, with the best efficacy-safety profile 3, 2
• Enoxaparin (weight-adjusted dosing) is an alternative and is at least as effective as unfractionated heparin with easier administration 3, 5
• Unfractionated heparin (weight-adjusted IV bolus followed by continuous infusion, aPTT target 1.5-2.5 times control) can be used if LMWH or fondaparinux are unavailable 3

Anti-Ischemic Medications

• Administer sublingual or IV nitroglycerin for ongoing chest pain unless systolic BP <90 mmHg, >30 mmHg below baseline, severe bradycardia <50 bpm, or tachycardia >100 bpm without heart failure 1, 2
• Initiate beta-blockers early in patients without contraindications (heart failure, hypotension, bradycardia, or heart block) 1, 3
• Administer morphine IV or subcutaneously only for patients with persisting severe chest pain despite nitroglycerin 1
• Apply oxygen therapy only if blood oxygen saturation <90% or respiratory distress is present 1

Immediate Statin Therapy

• Initiate high-intensity statin therapy immediately regardless of baseline cholesterol, as statins reduce recurrent ischemic events through plaque stabilization and anti-inflammatory effects 1, 4

Risk Stratification and Timing of Invasive Strategy

Very High-Risk: Immediate Angiography (<2 Hours)

Proceed immediately to catheterization laboratory if ANY of the following are present: 1, 4, 2

• Hemodynamic instability or cardiogenic shock
• Recurrent or ongoing chest pain refractory to medical treatment
• Life-threatening arrhythmias (ventricular fibrillation or ventricular tachycardia) or cardiac arrest
• Mechanical complications of MI (papillary muscle rupture, ventricular septal defect, free wall rupture)
• Acute heart failure with refractory angina or ST deviation

High-Risk: Early Angiography (<24 Hours)

Perform coronary angiography within 24 hours if ANY of the following are present: 1, 4

• Rise or fall in cardiac troponin compatible with MI
• Dynamic ST-segment or T-wave changes (≥2 mm ST depression or deep negative T waves)
• GRACE risk score >140 (this is the primary determinant for early invasive strategy timing in stabilized patients)

The GRACE score >140 threshold is validated by the TIMACS trial, which demonstrated that early intervention (median 14 hours) reduced the primary ischemic endpoint from 21.0% to 13.9% (HR 0.65, P=0.006) in patients with GRACE >140, while no benefit was seen in lower-risk patients 4

Intermediate-Risk: Invasive Strategy Within 72 Hours

• Patients with GRACE score ≤140 without recurrence of symptoms can undergo angiography within 72 hours at the first opportunity depending on local circumstances 1

Low-Risk: Conservative Strategy (Selective Angiography)

Patients fulfilling ALL of the following criteria may be managed conservatively: 1, 3

• No recurrence of chest pain
• No signs of heart failure
• No abnormalities in initial or 6-9 hour ECG
• No rise in troponin level (at arrival and at 6-9 hours)
• GRACE score <109

Before discharge, perform stress testing for inducible ischemia to determine need for elective angiography 1

Revascularization Strategy (For Patients Undergoing PCI)

• Radial access is preferred over femoral access to reduce bleeding, vascular complications, and death 1, 2
• Drug-eluting stents are recommended over bare-metal stents for any PCI to reduce restenosis rates 4, 2
• Intracoronary imaging is recommended to guide PCI in patients with complex coronary lesions 1
• Complete revascularization is recommended in patients with STEMI or NSTE-ACS; the choice between CABG versus multivessel PCI should be based on coronary disease complexity (SYNTAX score) and comorbidities 1
• Do not change anticoagulant during PCI; in patients pre-treated with fondaparinux, add UFH before PCI 1
• Consider GP IIb/IIIa inhibitor (eptifibatide or tirofiban) if troponins are elevated or angiographic thrombus is present 1

Long-Term Secondary Prevention (Post-Discharge)

Antiplatelet Therapy

• Continue aspirin plus P2Y12 inhibitor for 12 months, then transition to aspirin monotherapy indefinitely 1, 2
• In patients who have tolerated ticagrelor, transition to ticagrelor monotherapy ≥1 month after PCI to reduce bleeding risk 1

Cardiovascular Medications

• Beta-blocker therapy is mandatory in patients with LVEF ≤40%, unless contraindicated 1, 2
• ACE inhibitor (or ARB if ACE inhibitor not tolerated) is mandatory in patients with LVEF ≤40%, heart failure, hypertension, or diabetes 1, 2
• Mineralocorticoid receptor antagonists (preferably eplerenone) are mandatory in patients with LVEF ≤35% and either heart failure or diabetes, but no significant renal dysfunction or hyperkalemia 1
• Continue high-intensity statin long-term; obtain fasting lipid panel 4-8 weeks after initiating or adjusting dose to titrate to LDL-C <1.8 mmol/L (<70 mg/dL) 1

Lifestyle and Rehabilitation

• Advise all patients on smoking cessation, regular physical activity, and healthy diet 1
• Refer to cardiac rehabilitation program (home-based programs are acceptable for patients unable or unwilling to attend in person) 1
• Target diastolic blood pressure <90 mmHg (<85 mmHg in diabetic patients) 1

Special Populations and Dose Adjustments

Renal Impairment

• Adjust anticoagulant and antiplatelet doses according to renal function; declining renal function is a major cause of excess dosing and bleeding in elderly patients 3, 6
• Use low- or iso-osmolar contrast if angiography is performed 3

Elderly Patients (≥75 Years)

• Apply the same diagnostic and therapeutic strategies as younger patients 3, 4
• Reduce prasugrel dose to 5 mg daily if used 3, 4
• Adjust antithrombotic dosing based on renal function and bleeding risk 3

Patients Requiring Oral Anticoagulation (e.g., Atrial Fibrillation)

• Transition from triple therapy (aspirin + clopidogrel + OAC) to dual therapy (OAC + clopidogrel) after the acute phase (up to 1 week), as triple therapy significantly increases bleeding risk 3, 4
• Discontinue aspirin 1-4 weeks after PCI with continued use of P2Y12 inhibitor (preferably clopidogrel) plus oral anticoagulant 1

Gastrointestinal Bleeding Risk

• Administer proton pump inhibitor in patients at risk for gastrointestinal bleeding 1
• Avoid omeprazole or esomeprazole with clopidogrel, as they significantly reduce antiplatelet activity; consider another acid-reducing agent with minimal CYP2C19 inhibitory effect 7

Critical Pitfalls to Avoid

• Do not delay aspirin or ECG while waiting for troponin results; these must occur within 10 minutes 2
• Do not use GRACE score for 6-month mortality when applying the >140 threshold for early invasive strategy; use the GRACE score for in-hospital death, as this is what the TIMACS and VERDICT trials validated 4
• Do not stop clopidogrel abruptly if CABG is planned; discontinue 5 days prior to scheduled surgery only if clinical condition and angiographic findings permit 1, 7
• Do not routinely monitor patients beyond 24-48 hours if treated with early revascularization, as 80% of life-threatening arrhythmias occur within the first 12 hours 1