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A. Introduction navigator

  1. Indications for CABG [1]
    1. Severe CAD when perutaneous coronary interventions (PCI) are unlikely to relieve lesions
    2. Significant anginal pain after stenting and/or maximal medical therapy
    3. Revascularization is superior to medical therapy for hybernating myocardium
    4. Preferred revascularization modality for diabetes mellitus (DM) patients [4]
    5. CABG is usually recommended first for left main coronary stenosis [3]
    6. Minimally invasive CABG for left anterior decending (LAD) disease may be superior to standard stenting [31]
    7. CABG and drug-eluting stents similar outcomes for unprotected left main CAD [27]
    8. CABG is superior to modern PCI+stenting for multivessel extensive CAD [2]
    9. CABG reduces need for revascularization versus PCI, but higher stroke rates [1]
  2. Consider CABG for the following Symptoms and Signs of CAD
    1. Symptoms - chest pain, shortness of breath, heart failure (CHF), arrhythmias
    2. Signs - arrhythmias, hypoxia, CHF
    3. Impending Severe Myocardial Ischemia - severe coronary disease (± symptoms)
    4. Revascularization can significantly improve function of hybernating myocardium
    5. Emergent: dissection during angioplasty, severe angina / infarction resistant to therapy
  3. Benefits of CABG
    1. Relief of chest pain which is resistant to medications (superior to PCI) [1]
    2. Subjective and objective improvement of functional status / exercise capacity
    3. Reduction in drug therapy required for anginal control and activity
    4. Proximal LAD or left main disease better treated with CABG than medications
    5. Sudden cardiac death: 1.6% following surgery versus ~4.5% with medical therapy
    6. CABG superior to angioplasty ± stents for severe CAD in patients on dialysis [39]
    7. PCI and CABG have similar 10 year survival [1]
  4. Stenting Versus CABG in Multivessel CAD [5,32]
    1. Two studies had similar outcomes for stroke, MI, and death 1 year after proceedure
    2. Revascularization within 1 year required in ~20% of stent versus ~5% of CABG patients
    3. Overall cardiac endpoints occur more with PCI±stenting than with CABG
    4. Similar differences observed in more modern study [2]
  5. Surgery Versus Angioplasty±Stent for Multivessel CAD [2]
    1. Overall 5 year survival was similar in angioplasty versus CABG
    2. Overall in-hospital mortality was ~1.2% (not significantly different between groups)
    3. Subsequent revascularization is always higher with PCI±stent compared with CABG
    4. Post-procedure angina usually somewhat higher with PCI±stent compared with CABG
  6. Serolimus-eluting stents probably superior to CABG for blocked small coronary arteries [42]
  7. Risk of surgical mortality and morbidity inversely related to EF

B. Overview of Procedurenavigator

  1. Goal is bypass of significant stenoses with vascular graft from aorta to distal site
  2. A coronary angiogram is required prior to surgery to evaluate disease
  3. In addition, the angiogram provides information on possible graft sites (touchdown points)
  4. Up to ~8 separate grafts can be placed in one operation
  5. Sternotomy [30,31]
    1. Classical proceedure utilizes long sternal incision
    2. Minimally invasive proceedures are being developed with smaller incisions
    3. Smaller incision may may compromise revascularization
    4. Smaller incision acceptable for bypassing LAD lesions [31]
  6. Cardiopulmonary Bypass (CPB)
    1. In original CABG procedure, heart is stopped (cardiac stasis) in a controlled setting
    2. Cardiac stasis achieved by instilling cold solution
    3. Recent trials using potassium as an anti-inotrope with maintenance of physiologic temperature (warm cardioplegia) have had very favorable results
    4. Thus, off pump bypass has been improved with similar results and less expense [34] but poorer graft patency compared with on pump surgery [38]
    5. In on pump surgery, cardiac bypass pump is initiated
    6. Advisable to maintin mild hypothermia (~34°C) during CABG, avoid rapid rewarming and hyperthermia in order to minimize risk of post-CABG cognitive impairment [48]
    7. Heart is restarted with electrical stimulation at completion of procedure
  7. Off Pump CABG [7,8,34,41]
    1. CPB pump is not required for effective surgery
    2. New stabilization devices permit grafting while heart continues pumping
    3. Off pump procedures produce less inflammation and coagulopathies than on pump
    4. Off pump CABG has reduced peri-operative and mid-term complications
    5. Hospitalization is shorter [34] or similar [38] with off pump versus on pump CABG
    6. Cost is lower for off pump bypass procedure versus on pump [34,41]
    7. Graft patency at 3 months was lower with off pump versus on pump (10% better) in one study [38] but not in another (no significant difference) [41]
    8. No differences in caognitive and cardiac outcomes at 5 years versus on-pump [20]
  8. In general, arterial grafts (usually internal mammary) are preferred over vein grafts [9]
    1. Arterial grafts have longer lifetime without reocclusion
    2. Internal mammary artery is typically used for at least one graft
    3. Compared with saphenous vein grafts, arterial grafts confer a survival benefit
    4. In selected patients, the radial artery can be used as a donor site
  9. Aspirin may be started safely within 48 hours and is associated with mortality reduction [33]
  10. Intensive insulin therapy to control glucose during CABG is not beneficial [13]

C. Complicationsnavigator

  1. Blood Loss
    1. Many patients will contribute an auto-donation >1 month prior to surgery
    2. Pharmacologic reduction of blood loss with hemorrhage sparing agents reduces overall mortality, need for transfusion, and repeat thoracotomy [10]
    3. Hemorrhage sparing agents include lysine analogs aminocaproic and tranexamic acids, and the serine protease (plasmin) inhibitor aprotonin (Trasylol®)
    4. Aminocaproic and tranexamic acids are lysine analogs that act as plasmin inhibitors, with good efficacy and side effect profiles [28]
    5. These agents may be considered in any high risk patients undergoing CABG
    6. "High Risk" is defined by underlying diseases, bleeding diathesis, others
    7. Aprotinin associated with 2X renal failure risk, 1.5X MI or CHF risk, 1.8X encephalopathy or stroke risk [17], and 1.3-1.8X increased mortality [22,28,50,51] versus lysine analogs
    8. Neither aminocaproic nor tranexamic acid was associated with an increased risk of renal, cardiac, central neurological, events, or overall morality [17,22,50,51]
    9. Aprotinin appears to be safe with respect to kidney function for on-pump cardiac surgery [49]
    10. Combined aprotinin and ACE inhibitors for off-pump cardiac surgery associated with significantly increased risk (1.8X) of post-operative renal dysfunction [49]
    11. Aprotinin use can no longer be justified [22,28,50,51]
    12. HemoSTATUS® bedside test is now available for assessment of platelet function in patients who are to undergo cardiac surgery
    13. Patients with abnormal results on HemoSTATUS may benefit from desmopressin
    14. Transfusion of red cells stored >2 weeks associated with increased postoperative complications and reduced survival [11]
  2. Cardiac Events
    1. Malignant Arrhythmias and Sudden Cardiac Death
    2. Atrial Fibrillation (and flutter)
    3. Myocardial Infarction - best evaluated with cardiac troponin levels (I or T)
    4. Pericarditis
    5. CHF (see below)
    6. Cardiac Pseudoaneurysm
  3. Pericarditis
    1. Due to irritation of pericardium
    2. May precipitate atrial fibrillation
  4. Atrial Fibrillation (AFib) and Flutter [14,40]
    1. Occurs in ~40% of patients peri- and post-CABG
    2. Increasing incidence with age at surgery (<5% in <40 year olds; >30% in >70 year olds)
    3. Concommitant valvular disease is an independent risk factor
    4. ß-blockers, ACE inhibitors (and diltiazem) reduce risk of post-operative AFib >70%
    5. Postoperative hydrocortisone (100mg IV night of the operation, then 100mg q8 hours for next 3 days) reduced AFib from 48% to 30% in 241 randomized patients [21]
    6. Preoperative amiodarone reduced risk of AFib by 40-50% in CABG patients [14,15,16,44]
    7. Oral amiodarone 10mg/kg 6 days prior to through 6 days after surgery reduced risk of AFib ~50% and sustained VTach >50% regardless of ß-blocker use [15]
    8. All patients should receive ß-blockers peri-CABG if not contraindicated
    9. ACE inhibitors or diltiazem should be considered in patients intolerant of ß-blockers
    10. Consider amiodarone in severe LV dysfunction and/or high risk for arrhythmias [44]
    11. Digoxin should NOT be used for prevention of AFib
  5. CHF
    1. Patients with reduced LV ejection fraction EF (<40%) are at high risk for severe CHF
    2. Myocardial muscle "stunning" appears to be major problem
    3. Inotropic support, typically with ß-agonists or milrinone/amrinone is usually used
    4. Intravenous thyroid hormone (triiodothyronine) is not generally effective for treatment of perioperative cardiac failure
  6. Reduction of Cardiac Events
    1. Acadesine to reduce cardiac events (see below)
    2. Aspirin within 48 hours of procedure reduces many of these events and is safe [33]
    3. Amiodarone prophylaxis reduces risk of atrial fibrillation, ventricular tachyarrhythmias, stroke and length of stay after cardiac surgery [15,44]
  7. Neurological Events [18,46,48]
    1. Stroke - usually due to clots formed in heart during bypass [48]
    2. Seizures
    3. Postoperative delirium
    4. Intellectual Deterioration - ~50% of patients at discharge, 40% long term [19]
    5. Cognitive outcomes similar at 1 and 5 years with or without CPB for CABG [20]
    6. Depression - independent risk factor for early death (~2.3X increased risk) [37]
    7. Overall, ~6% of patients undergoing CABG had adverse neurological events
    8. Neurologic event risks include aortic and carotid atherosclerosis, increased age, hypertension (HTN), systolic cardiac dysfunction
    9. Trend to reduced perioperative stroke when CABG at 31.4-33.1°C, versus >33.2°C [48]
    10. Mild hypothermia (~34°C) recommended during CABG [48]
  8. Renal Dysfunction
    1. Increased risk with time on heart-lung bypass (particularly >3 hours)
    2. Underlying renal disease is another major risk factor (especially diabetes)
    3. Underlying left ventricular dysfunction is also a major risk factor
    4. Patients who develop peri-CABG renal failure have much poorer prognosis than others
    5. Neutrophil gelatinase-associated lipocalcin levels can be used to predict acute renal injury after cardiac surgery [24]
    6. Perioperative N-acetylcysteine (4 doses of 600mg each IV) did not reduce the risk of renal dysfunction (creatinine increase >0.5mg/dL) in high risk CABG patients [43]
  9. Pulmonary Complications [12]
    1. Grade 1: Dry cough - microatelectasis, dyspnea, may be associated with fever
    2. Grade 2: Productive cough, bronchospasm, hypoxemia, transient hypercarbia
    3. Grade 3: Pleural effusion resulting in thoracocentesis, pneumonia, pneumothorax, reintubation
    4. Grade 4: Ventilatory faiilure: postoperative ventilator dependence >48 hours, or reintubation with subsequent period of ventilator dependence >48 hours
    5. Risk factors for pulmonary complications: age >70 years, cough and expectoration, diabetes mellitus, smoking, COPD with FEV1 <75% predicted, body mass index >27 kg/m2
    6. Preoperative intensive inspiratory muscle training reduced pulmonary complications ~50% compared with usual care group
  10. Pleural Effusions
    1. Small pleural effusions are fairly common (~50%)
    2. Large pleural effusions (>25% of hemithorax) occur in ~1% of patients
    3. Managed by therapeutic thoracocenteses
  11. Infection
    1. Increased incidence in high risk patients, particularly elderly
    2. Oral, "immune-enhancing" nutritional supplements reduce infections when given for at least 5 days prior to elective cardiac surgery [23]
    3. Chlorhexidine gluconate decontamination of nasopharynx and oropharynx does not reduce nosocomial infection risk associated with cardiac surgery [47]
  12. Readmission [6]
    1. Within 30 days, occurs in ~13% of patients
    2. Most commonly due to postsurgical infection and CHF
    3. Increased age, female sex, African American race, high body surface area all risk factors
    4. Previous MI within past week also associated with readmission
  13. Death
    1. Overall peri-operative mortality is 1-4%
    2. For all cardiac surgeries, cardiac failure contributes to >50% of deaths
    3. Peri-Operative mortality is similar for blacks and whites

D. Reducing Adverse Coronary Eventsnavigator

  1. Acadesine [25]
    1. Adenosine is a potent coronary vasodilator, particularly in ischemic tissue
    2. Acadesine is a nucleoside analog which increases tissue adenosine levels
    3. A meta-analysis of 5 trials using acadesine during CABG has shown benefit
    4. Acadesine given pre- and perioperatively reduces major morbidity in CABG patients
    5. Early cardiac death, MI, and combined adverse cardiovascular outcomes were reduced
    6. Average reduction of stroke was not significant, but other events reduced >25%
  2. ß-adrenergic Blockers
    1. Recommended for all patients without contraindications undergoing CABG
    2. Mortality in patients with LV EF <30% undergoing CABG reduced by 20% reduction [26]
    3. Reduce incidence of post-operative AFib ~50% [35]
  3. In patients at high risk for post-operative AFib, consider sotolol or amiodarone

E. Long-Term Postoperative Therapy [36] navigator

  1. All patients should take ASA (recommend 81-162mg/d) unless contraindicated by allergy or high-dose anticoagulation therapy
  2. Patients with history of MI should be taking a ß-adrenergic blocker
  3. Reduction of cholesterol levels to below pre-CABG baseline
  4. ACE inhibitors for all patients with reduced LV EF and/or HTN
  5. Smoking cessation is critical
  6. Exercise is strongly advocated, as tolerated
    1. CABG greatly improved exercise capacity and reduced angina
    2. Men and women improved equally
    3. Result of post-operative exercise testing does not correlate with quality of life
  7. Maintain relatively normal weight
  8. Additional anti-anginals as needed but are not required in many patients
  9. Periodic Exercise Stress
    1. Symptom limited exercise stress test
    2. Thallium (Nuclear Medicine) scanning adds value to detect ischemia
    3. Dobutamine echocardiography (PET / SPECT scans) can also detect ischemia
    4. Patients with reduced exercise capacity or thallium perfusion defects have 3- to 4-fold increased risk for major cardiac events including death within 3 years of CABG
    5. Postoperative stress tests may document increased viability of myocardium
  10. Depression
    1. Aggressive treatment of depression is essential to long term success [37]
    2. Citalopram (Celexa®) is significantly more effective than placebo or psychotherapy in patients with depression post-CABG [29]
  11. Evaluation for other atherosclerotic disease, particularly cerebrovascular

F. Coronary Artery Bypass Graft Disease [9] navigator

  1. Average lifespan of a vein (usually saphenous) graft is 5-8 years; 50% patency at 10 years
  2. Average lifespan of an arterial (usually internal mammary) is >10 years (90% patency)
  3. Treatment with antiplatelet agents decreases vein graft occlusion rate
  4. Aggressive lipid reduction (LDL <100mg/dL) but not warfarin improved angiographic vein graft patency; statins should be used in all patients with CAD
  5. Consider reoperation for symptoms due to atherosclerosis of LAD graft disease
  6. PTCA and/or stent placement can be used for obstructed grafts [19]
  7. Edifoligide, an E2F transcription factor decoy, does not affect vein graft failure at 1 year [45]

G. Prognosisnavigator

  1. Overall 1 year survival >90%, 5 year survival >75%
  2. Hypertension and diabetes mellitus (DM) are risk factors for increased mortality
  3. Smoking is a major contributor to morbidity and mortality
  4. HTN, DM and smoking are higher in blacks than in whites undergoing CABG
  5. Cardiac pseudoaneurysm is uncommon, and generally has a good outcome
  6. Preoperative IgM anti-endotoxin core Ab levels (not IgG) correlated with outcomes

References navigator

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