What is the role of Extracorporeal Membrane Oxygenation (ECMO) in patients with acute myocardial infarction?

ECMO in Acute Myocardial Infarction

ECMO may be considered as a short-term mechanical circulatory support option in patients with acute myocardial infarction complicated by refractory cardiogenic shock (SCAI stage D or E) who fail to respond to optimal medical therapy, but it should be reserved for carefully selected patients at experienced centers as a bridge to recovery, definitive therapy, or transplantation—not as routine therapy. 1

Clinical Context and Evidence Base

The role of ECMO in AMI-associated cardiogenic shock remains controversial with limited high-quality evidence. Multiple randomized trials of VA-ECMO in AMI cardiogenic shock are currently ongoing (EURO SHOCK, ECLS-SHOCK, ECMO-CS, ANCHOR), and results are pending to definitively guide practice. 1 Until these trials report, clinical decisions must rely on observational data showing mixed outcomes and significant complications.

When to Consider ECMO

Indications

ECMO should be considered when ALL of the following criteria are met:

• Refractory cardiogenic shock (SCAI stage D or E) despite maximal medical therapy including inotropes/vasopressors 1, 2
• Evidence of inadequate end-organ perfusion (elevated lactate >7 mmol/L, pH <7.2, oliguria, altered mental status) 1, 3
• Failure of or inadequate response to IABP support 1, 2
• Potentially reversible underlying cardiac pathology or bridge to definitive therapy (transplant, durable LVAD, recovery) 1, 2
• Absence of contraindications (see below) 1

Absolute Contraindications

Do NOT initiate ECMO if any of the following are present:

• Irreversible brain damage or severe neurological injury (Glasgow Coma Scale <8 with unfavorable prognostic features after cardiac arrest) 1, 2
• Unwitnessed cardiac arrest with prolonged CPR >30 minutes without return of spontaneous circulation 1
• Advanced age (>85 years) with multiple comorbidities indicating poor recovery potential 1, 2
• End-stage renal disease or irreversible multi-organ failure 1
• No potential for cardiac recovery and patient not a candidate for transplant or durable MCS 1

Timing and Implementation Strategy

Pre-ECMO Management

Before considering ECMO, ensure the following have been optimized:

• Immediate coronary angiography with revascularization (PCI or CABG) if coronary anatomy is suitable 1, 4
• Invasive arterial blood pressure monitoring 1
• Immediate echocardiography to assess ventricular function and exclude mechanical complications (ventricular septal defect, acute mitral regurgitation, free wall rupture) 1
• Inotropic support (dobutamine) and vasopressor therapy (norepinephrine preferred) 2
• IABP placement attempted first in most cases 1

ECMO Configuration and Insertion

Veno-arterial (VA) ECMO is the configuration of choice for AMI cardiogenic shock as it provides both cardiac and respiratory support. 2 Peripheral cannulation via femoral vessels allows rapid bedside insertion. 1

Critical timing consideration: Early ECMO initiation (before irreversible end-organ damage) yields better outcomes. 5, 3 In one study, the period between CPR initiation and ECMO commencement was a significant predictor of weaning failure, and pre-ECMO serum lactate >7 mmol/L predicted mortality. 3

Expected Outcomes and Complications

Survival Data

Observational studies show highly variable outcomes:

• Hospital survival ranges from 30-79% in published series 6
• 12-month survival ranges from 23-36% 6
• Mean ECMO support duration: 2-6 days (range 1-141 hours) 5, 6, 3
• Successful weaning from ECMO: 70-82% of patients 5, 3

Major Complications

ECMO carries substantial risks that must be weighed against potential benefits:

• Bleeding complications (gastrointestinal bleeding 3.6%, major bleeding requiring transfusion common) 6
• Vascular complications and limb ischemia (8.5%) 6
• Acute renal failure requiring dialysis (common) 3
• Pneumonia and infectious complications (common) 3
• Thromboembolic events 3
• Hemolysis 1

Special Populations

Cardiac Arrest Patients

**For comatose patients (Glasgow Coma Scale <8) after cardiac arrest with AMI cardiogenic shock, initiate targeted temperature management immediately and individualize early invasive therapy based on absence of multiple unfavorable prognostic features.** 1 Unfavorable features include: unwitnessed arrest, non-shockable rhythm, no bystander CPR, >30 minutes to ROSC, pH <7.2, lactate >7 mmol/L, age >85 years. 1

Patients with ongoing cardiac arrest without return of spontaneous circulation represent the highest-risk group; ECMO with automated CPR has been reported successful only in carefully selected patients by experienced teams at tertiary centers. 1

Bridge Strategies

ECMO serves multiple bridging functions in AMI cardiogenic shock:

• Bridge to decision (BTD): Stabilize hemodynamics and end-organ function while evaluating for transplant or durable LVAD candidacy 1
• Bridge to recovery (BTR): Support until native cardiac function recovers (typical duration: days to weeks) 1, 2
• Bridge to bridge (BTB): Transition to more durable MCS device 1, 2
• Bridge to transplantation (BTT): Maintain patient until donor organ available 1

Multidisciplinary Decision-Making

Device selection requires input from a multidisciplinary shock team with consideration of patient hemodynamic profile, underlying shock mechanism (LV vs RV vs biventricular failure), respiratory status, and institutional expertise. 1

VA-ECMO is particularly suited for patients with biventricular failure and/or concurrent respiratory failure, whereas isolated LV failure may be better supported with Impella or TandemHeart. 1

Critical Pitfalls to Avoid

• Do not delay coronary revascularization to place ECMO; revascularization remains the definitive therapy 1, 4
• Do not use ECMO routinely or prophylactically; reserve for refractory shock only 1
• Do not continue ECMO support indefinitely without a clear exit strategy (recovery, durable device, or transplant) 1
• Do not initiate ECMO in patients with irreversible neurological injury or those who are not candidates for any definitive therapy 1, 2
• Recognize that ECMO increases LV afterload and may worsen LV distension; consider LV venting strategies in selected cases 1

Current Practice Recommendation

Given the lack of randomized trial data showing mortality benefit and the significant complication rates, ECMO should be used cautiously and selectively in AMI cardiogenic shock, primarily at experienced centers with established shock teams and ECMO programs. 1 The decision to initiate ECMO must be made early (before irreversible organ damage) but only after optimizing medical therapy and achieving revascularization. 2, 3