What is the role of Impella (left ventricular support device) in high-risk Percutaneous Coronary Intervention (PCI) procedures?

Role of Impella in High-Risk Percutaneous Coronary Intervention

In selected high-risk patients, elective insertion of an Impella device as an adjunct to PCI may be reasonable to prevent hemodynamic compromise during complex coronary interventions, though routine use has not been shown to reduce cardiovascular events. 1

Definition and Classification of High-Risk PCI

High-risk PCI typically involves patients with:

• Severely depressed left ventricular function (ejection fraction ≤35%) 2
• Complex coronary lesions including:
  • Unprotected left main disease 2
  • Last patent coronary conduit 2
  • Multivessel disease in patients with reduced cardiac reserve 3
• Risk of hemodynamic instability during the procedure 1

Impella Device Characteristics

• The Impella is a miniaturized percutaneous left ventricular assist device that provides continuous-flow, axial pump support with an external controller 4
• Available models include:
  • Impella 2.5: Provides up to 2.5 L/min of flow 4, 2
  • Impella CP: Provides greater support than 2.5 model 3
  • Impella RP: Designed specifically for right ventricular support 4
• The device works by directly unloading the left ventricle and increasing systemic perfusion 1

Evidence for Use in High-Risk PCI

Guideline Recommendations

• Current guidelines (2021 ACC/AHA/SCAI) give Impella support during high-risk PCI a Class IIb recommendation with Level of Evidence B-R 1
• This indicates that elective insertion "may be reasonable" in selected high-risk patients 1

Clinical Evidence

• The PROTECT II trial comparing Impella with intra-aortic balloon counterpulsation (IABP) for high-risk PCI was halted for futility after interim analysis showed no benefit in the primary endpoint of major adverse cardiac events 1
• However, Impella provided better hemodynamic support compared to IABP 1
• Small studies have demonstrated that Impella can maintain hemodynamic stability during high-risk procedures without being associated with significant vascular complications 3
• The PROTECT I trial showed that Impella 2.5 was safe, easy to implant, and provided excellent hemodynamic support during high-risk PCI 2

Advantages of Impella Support

• Provides greater left ventricular support than IABP 1, 4
• Allows for straightforward percutaneous insertion and rapid initiation of circulatory support 4
• Maintains stable hemodynamic conditions even when complications occur during PCI 5
• Can significantly increase aortic pressure during support 5
• May reduce major procedural complications (prolonged hypotension, ventricular tachycardia/fibrillation, cardiopulmonary arrest) 1

Limitations and Contraindications

• Maximum flow limitations, particularly for Impella 2.5, may be inadequate for patients with large body mass index or severe cardiogenic shock 4
• Contraindicated in patients with:
  • Left ventricular thrombus 1, 4
  • Aortic stenosis 1, 4
  • Severe peripheral artery disease 1, 4
  • Aortic disease 1, 4
• Potential for hemolysis, which occurs more frequently with Impella than with other support devices 5
• Risk of vascular and bleeding complications at access site 6

Strategies to Minimize Complications

• Femoral skills training for operators 6
• Standardized protocols for:
  • Optimizing vascular access 6
  • Closure techniques 6
  • Anticoagulation management 6
  • Post-procedural care 6
• Careful patient selection by heart team discussion for patients declined for surgery 7

Practical Approach to Impella Use in High-Risk PCI

1. Patient selection: Identify patients with poor left ventricular function (EF ≤35%) and complex coronary anatomy who are at risk for hemodynamic compromise during PCI 2

2. Heart team discussion: Particularly for patients declined for surgical revascularization 7

3. Pre-procedure planning:

   • Assess for contraindications (LV thrombus, aortic stenosis, peripheral artery disease) 1, 4
   • Select appropriate Impella device based on required level of support 4

4. Procedural considerations:

   • Ensure proper device placement (achieved in 85-95% of cases) 5
   • Monitor hemodynamic parameters throughout the procedure 5
   • Typical support duration is approximately 1-2 hours 2, 7

5. Post-procedure management:

   • Monitor for access site complications 6
   • Assess for signs of hemolysis 5
   • Median hospital stay after Impella-supported PCI is approximately 3 days 7

Conclusion

While the routine use of hemodynamic support devices for complex PCI has not been shown to reduce cardiovascular events, Impella may provide valuable hemodynamic support in carefully selected high-risk patients undergoing complex coronary interventions. The decision to use Impella should be based on patient-specific risk factors and the complexity of the planned intervention.