Coronary Artery Bypass Grafts Are Not Routinely Removed
Coronary artery bypass grafts (CABG) are permanent surgical implants that are not removed—they remain in place for the patient's lifetime, even when they fail or become diseased. When bypass grafts fail or native coronary disease progresses, the treatment approach is either repeat bypass surgery (redo CABG) or percutaneous coronary intervention (PCI), not graft removal 1.
Why Grafts Are Not Removed
The grafts become incorporated into the patient's vascular anatomy and removing them would cause more harm than benefit. The surgical approach to failed grafts focuses on:
- Creating new bypasses around failed grafts rather than extracting the old ones 1
- Leaving patent grafts undisturbed, particularly the left internal mammary artery (LIMA) to the LAD, which must be carefully preserved during any reoperation 1
- Managing diseased vein grafts as potential embolic sources during reoperation without attempting removal 2
Management of Failed Bypass Grafts
Redo CABG Surgery
Reoperation after previous CABG carries a 3-fold increased risk of hospital mortality compared to primary CABG 1. The ACC/AHA provides specific indications:
Class I Indication:
- Disabling angina despite maximal medical therapy (with objective evidence of ischemia if angina is atypical) 1
Class IIa Indication:
- Bypassable distal vessels with large areas of threatened myocardium documented by noninvasive studies 1
Critical surgical considerations during redo CABG:
- Sternal reentry is problematic and requires meticulous technique to avoid injury to underlying structures 2
- Patent LIMA grafts to the LAD must not be injured, as losing this conduit represents a major negative factor in long-term outcomes 1
- Diseased patent vein grafts can be sources of thromboembolism during manipulation 2
- Retrograde cardioplegia is essential for myocardial protection, especially when occluded coronaries are supplied by patent arterial grafts 2
Percutaneous Coronary Intervention (PCI)
PCI has become the preferred approach for many patients with previous CABG, particularly when applied to native vessels rather than vein grafts 1. The guidelines note:
- PCI to native vessels yields markedly superior results compared to vein-graft PCI 1
- Operators increasingly use SVGs as conduits to facilitate native-vessel PCI rather than pursuing direct SVG intervention due to higher complication rates 3
- The relative utility of percutaneous techniques is increased in the redo situation, especially for native vessel disease 1
Special Scenario: Functioning LIMA with Recurrent Ischemia
When a functioning LIMA graft to the LAD is present with ischemia in other territories, there is additional caution against reoperation 1. The ACC/AHA designates this as:
Class IIb (may be considered):
- Ischemia in non-LAD distribution with patent LIMA to LAD, without aggressive medical management and/or percutaneous revascularization attempts first 1
This reflects the critical importance of preserving the LIMA-LAD graft, which provides the best long-term patency of any conduit 4.
Outcomes of Redo CABG
Despite higher operative risk, long-term survival after redo CABG is comparable to PCI in appropriately selected patients 2. Key outcome data:
- In-hospital mortality is 2-5 times higher than primary CABG, though outcomes have improved in recent years 2
- Redo CABG should be limited to patients with jeopardized LAD territory that is viable 2
- CABG is preferable to PCI in patients with multiple diseased vein grafts and low cardiac function 2
Common Pitfall to Avoid
Do not confuse "removing a bypass" with emergency CABG after failed PCI. Emergency CABG for failed angioplasty is an entirely different scenario involving new bypass creation for acute vessel closure, not removal of existing grafts 1. This carries Class I indication for ongoing ischemia or hemodynamic compromise 1.