What is the optimal management strategy for a patient presenting with chest pain suspected to be due to acute coronary syndrome (ACS), particularly regarding percutaneous coronary intervention (PCI)?

Optimal Management Strategy for PCI in Acute Coronary Syndrome

Immediate Triage Based on ECG and Clinical Presentation

For STEMI patients, perform primary PCI within 90 minutes of hospital arrival (door-to-balloon time <90 minutes) at a facility performing >200 PCIs annually with operators performing >75 PCIs per year. 1 If PCI cannot be achieved within 120 minutes, administer fibrinolytic therapy with door-to-needle time <30 minutes, then transfer for PCI within 24 hours. 1, 2

For NSTE-ACS patients with unstable features (refractory angina despite optimal medical therapy, hemodynamic instability, cardiogenic shock, acute pulmonary edema, electrical instability, or worsening mitral regurgitation), perform immediate invasive strategy with coronary angiography <2 hours from hospital admission with intent to revascularize. 1, 3 These patients should be immediately transferred to a PCI-capable facility if presenting at a non-PCI center. 1

Risk Stratification for NSTE-ACS Without Immediate High-Risk Features

High- and Intermediate-Risk Patients (Routine Invasive Strategy)

Patients with GRACE risk score >140, elevated troponins, dynamic ST-segment changes, or recurrent ischemia should undergo coronary angiography within 24 hours. 1, 3 This routine invasive approach reduces death or MI by 18% and MI by 25% compared to selective invasive strategies. 1

The following criteria identify high-risk patients requiring early invasive strategy within 24 hours: 1, 3

• Elevated high-sensitivity troponin with dynamic changes
• GRACE risk score >140
• New or dynamic contiguous ST-segment or T-wave changes
• Transient ST-segment elevation (even if resolved at presentation)
• Recurrent chest pain despite medical therapy
• Marked ST-segment depression suggesting ongoing ischemia

Low-Risk Patients (Selective Invasive Strategy)

For low-risk NSTE-ACS patients with normal cardiac biomarkers, no recurrent symptoms, no heart failure signs, and normal or non-diagnostic ECG, perform noninvasive stress testing or coronary CT angiography prior to hospital discharge rather than routine early angiography. 1, 4 These patients derive less benefit from routine invasive approaches and should only proceed to angiography if noninvasive testing reveals high-risk features or if symptoms recur. 1

Low-risk criteria requiring selective approach include: 1

• No recurrence of chest pain
• No signs of heart failure
• No abnormalities in initial or 6-9 hour ECG
• No troponin rise at arrival and 6-9 hours
• GRACE risk score ≤140

Timing of PCI for NSTE-ACS

The optimal timing follows this algorithm: 1, 3, 5

• <2 hours: Hemodynamic instability, cardiogenic shock, refractory angina, electrical instability, heart failure
• **<24 hours**: GRACE >140, elevated troponins with dynamic changes, transient ST-elevation, marked ST-depression
• 24-72 hours: Intermediate-risk patients (TIMI 3-4) without immediate high-risk features
• >72 hours: Avoid in high-risk patients as this timing is associated with significantly worse outcomes 5

For high-risk NSTE-ACS patients (TIMI 5-7), PCI performed after 72 hours shows significantly worse primary outcomes compared to PCI within 24-72 hours and should be avoided. 5 For low-risk patients, routine early PCI <24 hours provides no benefit and may increase complications. 5

Pre-PCI Pharmacological Management

Administer immediately upon ACS diagnosis: 6, 3

• Aspirin: 150-300 mg loading dose (non-enteric), then 75-100 mg daily
• P2Y12 inhibitor: Clopidogrel 600 mg, prasugrel, or ticagrelor loading dose
• Anticoagulation: Unfractionated heparin (5000 IU bolus, titrate to ACT >250 seconds during PCI) or enoxaparin or bivalirudin
• Nitroglycerin: Sublingual or IV for ongoing chest pain
• Beta-blocker: Oral or IV unless contraindicated (heart failure, hypotension, bradycardia, heart block)

Do not switch anticoagulants during PCI. 1 If pre-treated with fondaparinux, add UFH before PCI. 1 Consider GP IIb/IIIa inhibitors (tirofiban or eptifibatide) for high-risk anatomy or elevated troponins. 1

Revascularization Decision After Angiography

For single-vessel disease, perform PCI with stenting of the culprit lesion. 1 For multivessel disease, the Heart Team should decide between PCI and CABG based on coronary anatomy, with consideration of sequential approach (culprit lesion PCI followed by elective CABG for non-culprit lesions with proven ischemia or FFR assessment). 1

If coronary anatomy is not favorable for PCI, perform emergency CABG. 6 This is particularly critical in cardiogenic shock or mechanical complications (severe acute mitral regurgitation, free wall rupture). 6

Critical Caveats

Wellens syndrome (biphasic T waves in V2-V3 or deep symmetric T-wave inversions in V1-V4 with history of chest pain and normal/minimal biomarkers) requires urgent PCI regardless of TIMI score, as it indicates critical proximal LAD stenosis with imminent large anterior MI. 7 Conventional TIMI risk stratification may underestimate risk in these patients. 7

For patients with chronic kidney disease, use low/iso-osmolar contrast at lowest volume and adjust anticoagulant doses based on renal function. 3, 4 Advanced kidney disease not on dialysis requires careful risk-benefit assessment due to contrast nephropathy risk. 4

Elderly patients require the same diagnostic and therapeutic strategies but with antithrombotic dosing adjusted for renal function and careful evaluation of frailty status. 3, 4

Do not routinely use intra-aortic balloon pump in cardiogenic shock without mechanical complications. 6 Consider only for mechanical complications related to NSTE-ACS. 6