What is the recommended inpatient workup and management for a patient presenting with Acute Coronary Syndrome (ACS)?

ACS Inpatient Workup and Management

All patients with suspected ACS must undergo immediate 12-lead ECG within 10 minutes of presentation, continuous cardiac monitoring, high-sensitivity troponin testing (with results available within 60 minutes and repeated at 1-3 hours), and initiation of dual antiplatelet therapy with aspirin plus a P2Y12 inhibitor alongside parenteral anticoagulation. 1, 2

Immediate Assessment (First 10 Minutes)

ECG and Monitoring

• Obtain 12-lead ECG within 10 minutes of first medical contact to distinguish STEMI from NSTE-ACS, as STEMI requires immediate reperfusion while NSTE-ACS follows a risk-stratified approach 1, 2, 3
• Initiate continuous cardiac rhythm monitoring immediately for arrhythmia detection and multi-lead ischemia monitoring 1, 2

Vital Signs Assessment

• Measure systolic blood pressure, heart rate, and perform cardiopulmonary auscultation 1
• Assess for hemodynamic instability, signs of heart failure (Killip classification), and respiratory distress 1, 2

Initial Blood Work

Blood work on admission must include 1:

• High-sensitivity cardiac troponin T or I (preferably) with results available within 60 minutes
• Serum creatinine
• Hemoglobin and hematocrit
• Platelet count
• Blood glucose
• INR in patients on vitamin K antagonists

Repeat troponin measurement at 1-3 hours if high-sensitivity assays are used 1

Immediate Pharmacological Management

Antiplatelet Therapy

• Administer aspirin 150-300 mg loading dose immediately to all patients without contraindications 2, 4, 5
• Initiate dual antiplatelet therapy (DAPT) with ticagrelor as the preferred P2Y12 inhibitor (180 mg loading dose, then 90 mg twice daily) for all patients at moderate to high risk of ischemic events 6, 2
• Alternative P2Y12 inhibitors include prasugrel or clopidogrel (300 mg loading dose, then 75 mg daily), though clopidogrel is less preferred due to CYP2C19 genetic variability affecting its efficacy 4, 5

Anticoagulation

Anticoagulation is obligatory and should be started at diagnosis 6:

• Unfractionated heparin (UFH): 70-100 IU/kg IV bolus (or 50-70 IU/kg if used with GP IIb/IIIa inhibitor), targeting activated clotting time of 250-350 seconds 6, 5
• Low molecular weight heparin (LMWH): At least as effective and safe as UFH 2, 5, 7
• Fondaparinux: Recommended when medical treatment is planned or logistical limitations prevent timely PCI 6
• Never switch between UFH and LMWH 6

Symptom Management

• Sublingual or intravenous nitrates for ongoing chest pain 1, 2
• Morphine (IV or subcutaneous) or alternative opiates reserved for patients with persisting severe chest pain 1
• Oxygen therapy only if arterial oxygen saturation <90% or respiratory distress—routine oxygen in normoxic patients is not beneficial 1

Beta-Blockers

• Initiate beta-blockers in the absence of contraindications (heart failure, hemodynamic instability) 2, 5

Risk Stratification and Invasive Strategy Timing

Very High-Risk Criteria (Immediate Invasive Strategy <2 Hours)

Proceed to immediate coronary angiography regardless of ECG or biomarker findings for 1, 6, 2:

• Hemodynamic instability or cardiogenic shock
• Ongoing myocardial ischemia with regional wall motion abnormality on echocardiography
• Life-threatening arrhythmias (ventricular fibrillation or ventricular tachycardia)
• Recurrent angina despite intense antianginal treatment with ST depression ≥2 mm or deep negative T waves

Place defibrillator patches in case of ongoing ischemia until urgent revascularization is performed 1

High-Risk Criteria (Early Invasive Strategy <24 Hours)

Perform coronary angiography within 24 hours for patients with 1, 6, 2:

• Rise or fall in cardiac troponin compatible with MI
• Dynamic ST-segment or T-wave changes
• GRACE risk score >140

Intermediate-Risk (Invasive Strategy <72 Hours)

• Patients without recurrence of symptoms may undergo angiography within 72 hours 1

Low-Risk (Conservative Strategy)

Patients meeting ALL of the following criteria may be managed conservatively 1:

• No recurrence of chest pain
• No signs of heart failure
• Normal serial ECGs (initial and at 6-9 hours)
• No rise in troponin (at arrival and at 6-9 hours)
• No inducible ischemia on stress testing

Perform stress test for inducible ischemia before discharge or within 72 hours after discharge 1

Additional Diagnostic Considerations

Echocardiography

• Consider immediate echocardiography in patients with ongoing chest pain and inconclusive ECG to exclude alternative diagnoses (pulmonary embolism, pericarditis, aortic dissection) and identify focal wall motion abnormalities 1

Lipid Profile

• Assess lipid profile in the early phase of admission if NSTE-ACS is confirmed 1

Revascularization Strategy

Percutaneous Coronary Intervention (PCI)

• Radial access is the standard approach unless there are overriding procedural considerations 2
• Use drug-eluting stents (DES) over bare-metal stents for any PCI 2
• For STEMI, perform primary PCI within 120 minutes of presentation; if not achievable, administer fibrinolytic therapy (alteplase, reteplase, or tenecteplase at full dose for patients <75 years; half dose for ≥75 years) 2, 3, 5
• GP IIb/IIIa inhibitor should be considered if troponins are elevated or thrombus is present on angiography 1, 6

Coronary Artery Bypass Grafting (CABG)

• If P2Y12 inhibitors are being used, stop them and defer surgery only if clinical condition and angiographic findings permit 1

Long-Term Management Initiated During Hospitalization

Mandatory Therapies (Class I Recommendations)

• High-intensity statin therapy started as early as possible and maintained long-term 1, 5
• ACE inhibitor in patients with LVEF ≤40%, heart failure, hypertension, or diabetes (ARB if ACE inhibitor not tolerated) 1, 5
• Beta-blocker therapy in patients with LVEF ≤40% 1, 5
• Mineralocorticoid receptor antagonists (preferably eplerenone) in patients with LVEF ≤35% and either heart failure or diabetes, without significant renal dysfunction or hyperkalemia 1
• DAPT for 12 months unless high bleeding risk 2, 4

Blood Pressure Goals

• Diastolic blood pressure <90 mmHg (<85 mmHg in diabetic patients) 1

Lifestyle Counseling

• Advise all patients on smoking cessation, regular physical activity, and healthy diet 1
• Enroll in secondary prevention/cardiac rehabilitation program 1

Special Populations

Elderly Patients (≥75 Years)

• Apply the same diagnostic and interventional strategies as younger patients, with adjustments for antithrombotic agent dosage based on renal function 2
• Use half-dose fibrinolytic therapy if needed 3

Chronic Kidney Disease

• Use low- or iso-osmolar contrast media at the lowest possible volume 2
• Adjust anticoagulation dosing based on creatinine clearance 1

Diabetes

• Screen all patients with NSTE-ACS for diabetes and monitor blood glucose levels frequently 2

Hospital Unit Selection

• Patients with suspected NSTE-ACS should be observed in interdisciplinary emergency departments or chest pain units until MI is confirmed or ruled out 1
• Patients treated with early revascularization are at low risk (2.5%) for life-threatening arrhythmias, with 80% occurring in the first 12 hours; routine monitoring beyond 24-48 hours is not warranted 1

Critical Pitfalls to Avoid

• Do not routinely administer oxygen to normoxic patients—no demonstrated benefit and potential harm 1
• Do not switch between UFH and LMWH—increases bleeding risk 6
• Do not use clopidogrel as first-line P2Y12 inhibitor in high-risk patients—ticagrelor or prasugrel are superior 6, 2
• Do not delay troponin results beyond 60 minutes—critical for risk stratification 1
• Do not assign "NSTE-ACS unlikely" diagnosis without caution, especially in elderly and diabetic patients 1