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Coronary Artery Bypass Grafting (CABG) OUTCOMES

OPERATIVE MORTALITY:

Clinical Guidelines on Myocardial Revascularization have been issued by:
  • American

CAUSES OF DEATH:

​R
LONG-TERM OUTCOMES

  • Depends on complex interaction between patient and procedure related factors.
  • Patient related factors:
    • Anatomic distribution of CAD.
    • Extent and severity of coronary atherosclerosis.
    • Impact of ischemia on ventricular function.
    • Age and gender.
    • Overall health and co-morbidities.
    • Overall atherosclerotic burden.
    • Operative complications:
      • Stroke.
      • Permanent hemodialysis.
    • Rate of progression of the atherosclerosis in the native arteries.
    • Graft failure.
  • Procedure related factors:
    • Completeness of revascularization.
    • Myocardial Protection.
    • Conduit selection.
Return of Angina:

Defined as the first occurrence of angina of any intensity or duration unless it was associated on the same day with MI or death.
  • Almost inevitable.
  • By 12 years, 50% of operated patients have return of angina.
  • Overall non-risk-adjusted freedom from return of angina:
    • 95% at 1 year.
    • 82% at 5 years.
    • 61% at 10 years.
    • 38% at 15 years.
    • 21% at 20 years.
  • ​BARI Trial: Freedom from angina was 84% and 5 and 10 years.

 Indications and Contraindications 

​ACC/AHA Guidelines 2011:
  • Define significant stenosis as
    • 70% diameter narrowing
    • 50% for Left Main Stem )LMS)
    • Fractional flow reserve (FFR) <0.80 may also be considered significant.
    • Some recommendations use SYNTAX scores as surrogates for the extent and complexity of CAD
  • Goals of the Procedure:
    • To improve symptoms and/or improve survival
    • Improved survival,  is generally given greater weight when selecting a procedure.
    • In discussions of options, the patient should clearly understand the goal of the procedure (symptom relief, improved survival, or both) before a decision is made
 ESC/EACTS 2014 Guidelines :
  • Revised its recommendation to include the development and use of standardised, evidence-based, and interdisciplinary protocols for low-risk and common scenarios
  • However, in such cases, revascularization at the time of diagnostic angiography is recommended against in order to allow for full assessment of the optimal treatment strategy.
  • Multidisciplinary systematic evaluation is still  required for complex cases
​
The Society of Thoracic Surgeons (STS) and SYNTAX (Synergy between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery) scores are recommended by both guidelines for risk stratification to aid in clinical decision-making​.
INDICATIONS FOR CABG TO IMPROVE SYMPTOM 
ACC/AHA and ESC/EACT GUIDELINES
INDICATION
ACC/AHA
ESC/EACT
Significant stenosis and unacceptable angina despite medical therapy 
CLASS I
CLASS I
Significant stenosis and unacceptable angina in patients with medication contraindications or adverse effects, or patient preference
CLASS IIa
 
In a good candidate, CABG may be considered over PCI for complex three-vessel CAD (eg, STYNTAX score >22) with or without involvement of the proximal LAD artery
CLASS IIa
CLASS I
Transmyocardial laser revascularization (TLR) as an adjunct to CABG may be considered in patients with viable ischemic myocardium that is perfused by coronary arteries that are not amenable to grafting
CLASS IIb
 
INDICATIONS FOR CABG TO IMPROVE SURVIVAL
ACC/AHA and ESC/EACT GUIDELINES
INDICATION
ACC/AHA
ESC/EACT
LMS ( LEFT MAIN STEM) DISEASE
CLASS I
CLASS I
3VD WITH  OR WITHOUT PROXIMAL LAD DISEASE
CLASS I
CLASS I
2VD  WITH PROXIMAL LAD DISEASE
CLASS I
CLASS I
2VD WITHOUT PROXIMAL LAD DISEASE
CLASS IIa
(with extensive ischaemia)
CLASS IIb
1VD WITH PROXIMAL LAD DISEASE 
CLASS IIa
(with LIMA for longterm benefit)
CLASS I
1VD WITHOUT PROXIMAL LAD DISEASE 
CLASS III
CLASS IIb
LV DYSFUNCTION
CLASS IIa
(EF 35-50%)
CLASS IIb
EF < 25%)
CLASS I
​(EF <40%)
SURVIVORS OF SUDDEN CARDIAC DEATH WITH PRESUMED ISCHAEMIA MEDIATED VT
CLASS I
CLASS I
3VD: THREE VESSEL DISEASE       2VD: TWO VESSEL DISEASE
1VD: SINGLE VESSEL DISEASE      EF: EJECTION FRACTION
VT: VENTRICULAR TACHYCARDIA       LV: LEFT VENTRICULAR 
 
  

EMERGENCY CABG ​

  • Both ACC/AHA and ESC/EACTS provide guidance on emergency CABG.
  • ACC/AHA guidelines provide a CLASS I recommendation for emergency CABG in:
    • STEMI where
      • PCI has been impossible to perform or has failed
      • And the patient has persistent pain and ischaemia threatening a significant area of  myocardium despite medical therapy.
  • Other CLASS I indications for emergency CABG in the setting of STEMI include: 
    • Ventricular septal defect POST Ml
    • Papillary muscle rupture
    • Free wall rupture
    • Ventricular pseudo-aneurysm
    • Life-threatening ventricular arrhythmias
    • Cardiogenic shock.

Emergency CABG is NOT RECOMMENDED in the following cases:
  • Persistent angina but only a small area of ischaemia AND haemodynamically stable
  • No-reflow state (successful epicardial reperfusion with unsuccessful microvascular reperfusion)
  • Ventricular tachycardia (VT) with scar and no evidence of ischaemia

CABG after failed PCI

Class I:
  • Ongoing ischaemia or threatened occlusion with myocardium at risk 
  • Haemodynamic compromise:
    • without impairment of coagulation and
    • without a previous sternotomy 
Class IIa:
  • Haemodynamic compromise: 
    • with impairment of coagulation and
    • without a previous sternotomy 
  • Retrieval of a foreign body (fractured guidewire or stent) in a crucial location
Class Ilb
  • Hemodynamic compromise and previous sternotomy; emergency CABG may be considered

Comorbidities/Higher-Risk Cohorts

Diabetes Mellitus ​

​The ACC/AHA recommends CABG over PCI for improved survival in patients with comorbid DM and multivessel CAD, particularly with use of  LIMA GRAFT (CLASS I)
  • The recommendation was upgraded from class Ila in the 2011 guidelines to class I in the 2014 guidelines.
  • However, the use of BIMA is associated with increased risk of infection and should be considered only when the benefit outweighs the increased  risk (class llb). 

ACC)/AHA/AATS/PCNA/SCAl/STS 2014 Guidelines update provid the following recommendations for patients with stable IHD and DM:
  • Patients should receive medical therapy
  • Revascularization should be considered for patients with symptoms that remain inadequately controlled despite medical therapy
  • A Heart Team approach is beneficial in the evaluation of CABG versus PCI
  • Mortality risk appears to be lower with CABG than with PCI in most patients with DM and complex multivessel disease, but exceptions may be identified.

The ESC/EACTS guidelines recommend:
  • CABG as the revascularization modality of choice for improved survival in patients with DM and multivessel or complex (SYNTAX Score >22) CAD.
  • However, PCI can be considered as a treatment alternative in diabetic patients with multivessel disease and a low SYNTAX score <22.

Kidney Disease

ACC/AHA consider CABG as reasonable (CLASS llb) recommendations) In the setting of end-stage renal disease (ESRD), the for the following indications:
  • To improve survival for patients with LMS stenosis >50%
  • To improve survival and relieve symptoms resistant to medical therapy in patients with >70% stenosis in:
    • Three major vessels or
    • The proximal LAD artery plus one other major vessel
  • CABG should not be performed in patients with ESRD whose life expectancy is limited because of non-cardiac conditions.
The ESC/EACTS guidelines:
  • Prefer CABG over PCI for patients with multivessel CAD and chronic kidney disease (CKD) when surgical risk is acceptable and life expectancy is longer than 1 year
  • PCI is preferred for those patients with high surgical risk and/or life expectancy < 1 year but may be challenging in those with heavily calcified coronaries.
  • Considerations include delaying  CABG until the effects of angiography on renal function have subsided.

Valvular Disease 

ACC/AHA recommendations:
  • CLASS I:  AVR  for moderate - severe aortic stenosis undergoing CABG 
  • Ischemic mitral valve regurgitation (MR) that is not likely to be resolved with revascularization should have concurrent mitral valve repair or replacement with CABG
    • CLASS I For severe MR
    • CLASS Ila for moderate MR
    • CLASS llb for mild MR
  • CLASS I:  in concurrent valvular surgery,  intraoperative TOE ( transoesophageal echocardiography) should be performed 
ESC/EATS recommendations:
  • Perform CABG in patients with stenosis > 70% in a major vessel and an aortic/mitral valve surgery indication (CLASS I)
  • Consider CABG in patients with stenosis 50-70% in a major vessel and an aortic/mitral valve surgery indication (CLASS Ila)
  • Perform mitral valve surgery in severe MR and LVEF >30% with CABG (CLASS I)
  • Consider mitral valve surgery in moderate MR who are undergoing CABG (CLASS Ila)
  • Consider repair of moderate-to-severe MR in wih CABG who have LVEF <35% (CLASS Ila)
  • Consider aortic valve surgery in moderate aortic stenosis who are undergoing CABG (CLASS Ila)
PREOPERATIVE MANAGEMENT OF ANTIPLATELET THERAPY IN PATIENTS UNDERGOING CABG
RECOMMENDATION
2011
ACC/AHA
2012
​ACC/AHA
2014
​ACC/AHA
2014
​ESC/EACT
2012
​STS
Administer aspirin to CABG patients preoperatively 
100-325mg
CLASS I
CLASS I
81-325mg
​CLASS I
75-160mg
​CLASS I
Discontinue Aspirin 3-5 days preop for patients with increased risk of bleeding or those who refuse blood transfusion
 
 
 
CLASS I
CLASS IIa
For Non-Urgent CABG
Stop Clopidogrel > 5 days
Stop Ticagrelor > 5 days
Stop Prasugrel >7 days
To reduce blood transfusion 
​CLASS I
​CLASS I
CLASS I
​CLASS I
 
​In patients referred for urgent CABG, discontinue clopidogrel and ticagrelor for at least 24h  to reduce major bleeding complications 
​​CLASS I
 
​​CLASS I
 
 
​In patients referred for urgent CABG, discontinue eptifibatide and tirofiban for at least 2-4h and abciximab for at 12h
​​CLASS I
​Stop eptifibatide & tirofiban 4 hours
​​CLASS I 
​CLASS I
 
 
​Anticoagulant therapy: unfractionated heparin; discontinue enozaparin 12-24 h 
discontinue fondaparinux  24 h 
discontinue bivalirudin for 3h 
 
​​CLASS I
 
 
 
POSTOPERATIVE MANAGEMENT OF ANTIPLATELET THERAPY IN PATIENTS UNDERGOING CABG
RECOMMENDATION
2011
ACC/AHA
2014
​ACC/AHA
2014
​ESC/EACT
2012
​STS
Administer aspirin to CABG patients indefinitely 
100-325mg
​
CLASS I
81-325 mg
(81 mg with ticagrelor)
CLASS I
75-160mg

​​CLASS I
​CLASS I
Administer clopidogrel or ticagrelor, in addition to aspirin, for 12 months 
 
CLASS I
CLASS IIb
 
Clopidogrel (75 mg daily) is a reasonable alternative in patients ​intolerant or allergic to aspirin 
​CLASS IIa
​ 
CLASS I
​
In CABG after acute coronary syndromes, restart dual antiplatelet therapy when bleeding risk is diminished.
​​ 
 
  
​​CLASS I
​Once postoperative bleeding risk is decreased, consider testing of response to antiplatelet drugs, either with genetic testing or with point-of-care platelet function testing, to optimise antiplatelet drug effect and minimise thrombotic risk to vein grafts  
​​ 
 
​ 
​​CLASS IIb
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