Coronary Artery Bypass Grafting (CABG) Guidelines 

Updated: Apr 22, 2016
  • Author: Walter Tan, MD, MS; more...
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Issuing Organizations and Classifications

Clinical guidelines on myocardial revascularization have been issued by the following organizations:

  • American College of Cardiology (ACC)/American Heart Association (AHA)
  • European Society of Cardiology (ESC)/European Association for Cardio-Thoracic Surgery (EACTS)
  • Society of Thoracic Surgeons

Recommendations have been classified in both guidelines according to the level of evidence supporting the usefulness and efficacy of the procedure [1, 2] :

  • Class I - Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective
  • Class II - Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness or efficacy of a procedure or treatment
  • Class IIa - Weight of evidence or opinion is in favor of usefulness or efficacy
  • Class IIb - Usefulness or efficacy is less well established by evidence or opinion
  • Class III - Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful or effective, and in some cases may be harmful
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Treatment Strategy Selection

Both ACC/AHA and ESC/EACTS guidelines give a class I recommendation to the use of a Heart Team approach in determining treatment strategy and selection of appropriate revascularization procedure (ie, percutaneous coronary intervention [PCI] or coronary artery bypass grafting [CABG]). The ACC/AHA guidelines define a Heart Team as “a multidisciplinary team composed of an interventional cardiologist and a cardiac surgeon who jointly 1) review the patient’s medical condition and coronary anatomy, 2) determine that PCI and/or CABG are technically feasible and reasonable, and, 3) discusses revascularization options with the patient before a treatment strategy is selected.”

This approach is similar to the tumor board or “supreme court” approach to complex or high-risk cases, or where there are not enough data (gray areas). For instance, use in patients with unprotected left main or complex coronary artery disease (CAD) is recommended. [1] .

On the other hand, the 2014 ESC/EACTS guidelines revised its recommendation from previous guidelines to include the development and use of standardized, 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. [2]

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. [1, 2]

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Emergency CABG

Both ACC/AHA and ESC/EACTS provide guidance on the use of CABG as an emergency procedure. [1, 2]

ACC/AHA guidelines provide a class I recommendation for CABG in the context of an ST-segment elevation myocardial infarction (STEMI) in cases where PCI has been impossible to perform or has failed and the patient has persistent pain and ischemia threatening a significant area of myocardium despite medical therapy. [1]

Other class I indications for emergency open heart surgery in the setting of STEMI include the following:

  • Ventricular septal defect related to MI
  • Papillary muscle rupture
  • Free wall rupture
  • Ventricular pseudoaneurysm
  • Life-threatening ventricular arrhythmias
  • Cardiogenic shock.

Emergency CABG is not recommended in the following cases [1] :

  • Persistent angina but only a small area of ischemia AND hemodynamically stable
  • No-reflow state (successful epicardial reperfusion with unsuccessful microvascular reperfusion)
  • Ventricular tachycardia with scar and no evidence of ischemia

CABG after failed PCI

Recommendations for emergency CABG after failed PCI include the following:

  • Ongoing ischemia or threatened occlusion with myocardium at risk (class I)
  • Hemodynamic compromise without impairment of coagulation and without a previous sternotomy (class I)
  • Hemodynamic compromise with impairment of coagulation and without a previous sternotomy (class IIa)
  • Hemodynamic compromise and previous sternotomy; emergency CABG may be considered (class IIb)
  • Retrieval of a foreign body (eg, fractured guidewire or stent) in a crucial location (class IIa)

Emergency CABG should not be performed after failed PCI in the absence of ischemia or threatened occlusion, or if revascularization is impossible or futile because of target anatomy or a no-reflow state.

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Indications and Contraindications

For decisions and recommendations on revascularization, the ACC/AHA guidelines, released in 2011, define significant stenosis as ≥70% diameter narrowing (≥50% for left main CAD). Physiological criteria, such as fractional flow reserve ≤0.80, may also be considered significant. In addition, some recommendations use SYNTAX scores as surrogates for the extent and complexity of CAD. [1]

CABG may be performed to improve symptoms and/or improve survival, with the latter generally given greater weight when selecting a procedure. The guidelines note that 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. [1]

CABG for Symptom Improvement

Recommendations for CABG for symptom improvement are as follows [1, 2] :

  • Significant stenosis and unacceptable angina despite medical therapy (class I recommendation for both ACC/AHA and ESC/EACTS)
  • Significant stenosis and unacceptable angina in patients with medication contraindications or adverse effects, or patient preference (ACC/AHA 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 (ACC/AHA class IIa but ESC/EACTS 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 (ACC/AHA class IIb)

CABG for Survival Improvement

ACC/AHA and ESC/EACTS recommendations for CABG to improve survival are compared in Table 1, below. [1, 2]

Table 1. Indications for Coronary Artery Bypass Grafting (Open Table in a new window)

Indication ACC/AHA ESC/EACT
Left main disease Class I Class I
Three-vessel disease with or without proximal LAD artery disease Class I Class I
Two-vessel disease with proximal LAD artery disease Class I Class I
Two-vessel disease without proximal LAD artery disease Class IIa (with extensive ischemia) Class IIb
Single-vessel disease with proximal LAD artery disease Class IIa (with LIMA for long-term benefit) Class I
Single-vessel disease without proximal LAD artery disease Class III—Harmful Class IIb
LV Dysfunction Class IIa (EF 35% to 50%)



Class IIb (EF<35%)



Class I (EF<40%)
Survivors of sudden cardiac death with presumed ischemia-mediated VT Class I Class I
LAD = left anterior descending (artery); LV = left ventricle; LIMA= left internal mammary artery EF = ejection fraction; VT = ventricular tachycardia
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Comorbidities/Higher-Risk Cohorts

Diabetes mellitus

The ACC/AHA recommends CABG over PCI for improved survival in patients with comorbid diabetes mellitus (DM) and multivessel CAD, particularly with use of the left internal mammary artery (LIMA); the recommendation was upgraded from class IIa in the 2011 guidelines to class I in the 2014 guidelines. However, the use of bilateral internal mammary arteries is associated with increased risk of infection and should be considered only when the benefit outweighs the increased risk (class IIb). [1]

In a 2014 update of the guidelines for patients with stable ischemic heart disease (IHD), the American College of Cardiology (ACC)/American Heart Association (AHA)/American Association for Thoracic Surgery (AATS)/Preventive Cardiovascular Nurses Association (PCNA)/Society for Cardiovascular Angiography and Intervention (SCAI)/Society of Thoracic Surgeons (STS) provided the following recommendations for patients with stable IHD and DM [3] :

  • 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). [2]

Kidney Disease

In the setting of end-stage renal disease, the ACC/AHA consider CABG as reasonable (class IIb recommendations) for the following indications [1] :

  • To improve survival for patients with left main coronary artery stenosis ≥50%
  • To improve survival and relieve symptoms resistant to medical therapy in patients with ≥70% stenosis in three major vessels or in the proximal LAD artery plus one other major vessel

CABG should not be performed in patients with end-stage renal disease whose life expectancy is limited because of noncardiac conditions. [1]

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 of less than 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. [2]

Valvular Disease

The ACC/AHA recommendations for patients with valvular disease are as follows: [1]

  • Aortic valve replacement for patients with moderate or worse aortic stenosis undergoing CABG (class I)
  • Patients with ischemic mitral valve regurgitation that is not likely to be resolved with revascularization should have concurrent mitral valve repair or replacement while undergoing CABG (class I recommendation for severe regurgitation, class IIa for moderate regurgitation, class IIb for mild regurgitation)
  • In patients undergoing concurrent valvular surgery, intraoperative transesophageal echocardiography should be performed (class I)

The ESC/EATS recommendations include the following [2] :

  • 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 IIa)
  • Perform mitral valve surgery in patients with severe mitral regurgitation and LVEF >30% who are undergoing CABG (class I)
  • Consider mitral valve surgery in patients with moderate mitral regurgitation who are undergoing CABG (class IIa)
  • Consider repair of moderate-to-severe mitral regurgitation in patients undergoing CABG who have LVEF≤35% (class IIa)
  • Consider aortic valve surgery in patients with moderate aortic stenosis who are undergoing CABG (class IIa)

Carotid/Peripheral Artery Disease

The ACC/AHA guidelines provide the following recommendations for patients with comorbid carotid artery disease [1] :

  • Patients with significant carotid artery disease require a multidisciplinary team (cardiologist, cardiac surgeon, vascular surgeon, and neurologist) approach (class I)
  • Patients with high-risk features (ie, age >65 years, left main artery stenosis, PAD, hypertension, smoking, diabetes mellitus, history of stroke or transient ischemic attack [TIA]) should undergo carotid artery duplex screening (class IIa)
  • Carotid revascularization may be considered in CABG patients with previous TIA or stroke and significant (50-99%) carotid artery stenosis
  • Timing of carotid intervention (synchronous or staged) should be based on relative magnitude of cerebral and myocardial dysfunction or jeopardy (class IIa)
  • Carotid revascularization may be considered in patients with no history of TIA or stroke but severe bilateral (70-90%) carotid stenosis or unilateral severe carotid stenosis with contralateral occlusion (class IIb)

The ESC/EACTS guidelines for carotid artery revascularization in CABG patients include the following [2] :

  • Carotid endarterectomy (CEA) or carotid artery stenting (CAS) should be performed only by teams with demonstrated 30-day combined death-stroke rates of <3% in patients without previous neurologic symptoms and <6% in patients with previous neurologic symptoms (class I)
  • Indications for carotid revascularization should be individualized after discussion by a multidisciplinary team, including a neurologist (class I)
  • Timing of procedures (synchronous versus staged) should be dictated by local expertise and clinical presentation, with the most symptomatic territory targeted first (class IIa)
  • In patients with a history of TIA/stroke, carotid revascularization is recommended for 70-99% carotid stenosis in both men and women (class I) and may be considered for 50-69% carotid stenosis, depending on patient-specific factors and clinical presentation (class IIb)
  • In patients with no history of TIA/stroke, carotid revascularization may be considered in men with bilateral 70-99% carotid stenosis, 70-99% carotid stenosis and contralateral occlusion, or 70-99% carotid stenosis and ipsilateral previous silent cerebral infarction (class IIb)
  • Choice of carotid revascularization modality (CEA vs CAS) in patients undergoing CABG should be based on patient comorbidities, supra-aortic vessel anatomy, urgency of CABG, and local expertise (class IIa)
  • Acetylsalicylic acid (ASA) immediately before and after carotid revascularization (class I)
  • Dual antiplatelet therapy with ASA and clopidogrel for at least 1 month in patients undergoing CAS (class I)

The ESC/EACTS advise that CAS should be considered in patients with any of the following (class IIa):

  • Post-radiation or post-surgical stenosis
  • Obesity
  • Hostile neck
  • Tracheostomy
  • Palsy
  • Stenosis at different carotid levels or upper internal carotid artery stenosis
  • Severe comorbidities contraindicating CEA
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CABG Conduit Selection

The ACC/AHA guidelines make the following recommendations for bypass graft conduit selection [1] :

  • Left internal mammary artery (LIMA) to bypass left anterior descending (LAD) artery (class I)
  • Right internal mammary artery when LIMA is unavailable or unsuitable as a bypass conduit (class IIa)
  • When anatomically and clinically suitable, use of a second internal mammary artery to graft the left circumflex or right coronary artery is reasonable to improve survival and decrease likelihood of reintervention (class IIa).  This is weighed against the slightly increased risk of deep sternal wound infections in diabetics or the morbidly obese.
  • In patients ≤60 years old with few or no comorbidities, complete arterial revascularization may be considered (class IIb)
  • Arterial grafting of the right coronary artery when ≥90% stenosis (class IIb)
  • Radial artery graft when grafting left-sided arteries with severe stenosis (>70%)and right-sided arteries with critical stenosis (≥90%) that perfuse LV myocardium (class IIb)

Guidelines on conduit selection from by the Society of Thoracic Surgeons include the following recommendations:

  • Internal thoracic arteries (ITAs) should be used to bypass the LAD artery when bypass of the LAD is indicated
  • As an adjunct to left internal thoracic artery (LITA), a second arterial graft (right ITA or radial artery) should be considered in appropriate patients
  • Use of bilateral ITAs (BITAs) should be considered in patients who do not have an excessive risk of sternal complications
  • To reduce the risk of sternal infection with BITA, skeletonized grafts should be considered, smoking cessation is recommended, glycemic control should be considered, and enhanced sternal stabilization may be considered
  • As an adjunct to LITA to LAD (or in patients with inadequate LITA grafts), use of a radial artery graft is reasonable when grafting coronary targets with severe stenoses
  • When radial artery grafts are used, it is reasonable to use pharmacologic agents to reduce acute intraoperative and perioperative spasm
  • The right gastroepiploic artery may be considered in patients with poor conduit options or as an adjunct to more complete arterial revascularization
  • Use of arterial grafts (specific targets, number, and type) should be a part of the discussion of the heart team in determining the optimal approach for each patient
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Antiplatelet Therapy

Recommendations for the management of antiplatelet therapy in patients undergoing CABG have been provided by the following organizations:

  • American College of Cardiology (ACC)/American Heart Association (AHA) – For patients undergoing CABG [1] or those with unstable angina/non–ST-elevation myocardial infarction (NSTEMI) [4] or non–ST-elevation acute coronary syndromes [5]
  • European Society of Cardiology (ESC) – For patients undergoing CABG [6]

For preoperative management of antiplatelet therapy, see Table 2, below. [1, 4, 5, 6, 7]

Table 2. Preoperative management of antiplatelet therapy in patients undergoing CABG (Open Table in a new window)

Recommendation 2011 ACC/AHA 2012 ACC/AHA 2014 ACC/AHA 2014 ESC/EACT 2012



STS



Administer aspirin to CABG patients preoperatively (100 mg to 325 mg daily)



Class I



Class I (81–325 mg daily)



Class I



(75–160 mg daily)



Class I



 
In patients at increased risk for bleeding and those who refuse blood transfusion, discontinue aspirin 3-5 days prior to surgery       Class I Class IIa
For non-urgent CABG, discontinue clopidogrel and ticagrelor for at least 5 days before surgery and prasugrel for at least 7 days to limit blood transfusions Class I Class I Class I Class I  
In patients referred for urgent CABG, discontinue clopidogrel and ticagrelor for at least 24 hours to reduce major bleeding complications Class I   Class I    
In patients referred for urgent CABG, discontinue eptifibatide and tirofiban for at least 2-4 hours and abciximab for at 12 hours Class I (Discontinue eptifibatide and tirofiban 4 hours)



Class I



Class I    
Anticoagulant therapy: unfractionated heparin; discontinue enozaparin 12-24 hours; discontinue fondaparinux for 24 hours; discontinue bivalirudin for 3 hours   Class I      

For postoperative management of antiplatelet therapy, see Table 3, below. [1, 4, 5, 6, 7]

Table 3. Postoperative management of antiplatelet therapy in patients undergoing CABG (Open Table in a new window)

Recommendation 2011 ACC/AHA 2014 ACC/AHA 2014 ESC/EACT 2012



STS



Administer aspirin to CABG patients indefinitely 100 mg to 325 mg daily -



Class I



81–325 mg daily(Only 81 mg with ticagrelor)



Class I



75–160 mg daily



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 optimize antiplatelet drug effect and minimize thrombotic risk to vein grafts



      Class IIb
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