I. General Considerations

1. When a patient is considered a potential candidate for cardiac surgery, a comprehensive evaluation of their overall medical condition and comorbidities is essential. This includes a detailed history and physical examination, which may identify cardiac and noncardiac problems that may need to be addressed perioperatively to minimize postoperative morbidity (Table 3.1). On occasion, the presence of multiple comorbidities and/or a compromised quality of life may contraindicate a surgical procedure that might otherwise seem to be indicated from a cardiac perspective. Attention should also be paid to identifying new cardiac abnormalities that may have arisen since the initial cardiac evaluation that may warrant further work‐up. Baseline laboratory tests, if not recently performed, are also obtained, and further evaluation and consultation are performed, if indicated.
   
2. Evaluation of demographic factors, cardiac disease, and noncardiac comorbidities can provide the surgeon, the patient, and the patient’s family an insight into the risk of surgery. The Society of Thoracic Surgeons (STS) operative risk calculator is available online at www.sts.org and is updated every few years with an increasing number of data entry fields. This provides a reliable computerized assessment of mortality for most types of cardiac surgical procedures and also quantitates the risk of important postoperative morbidities, such as re‐exploration for bleeding, stroke, prolonged ventilation, and renal failure. In other countries, the additive and logistic EuroSCORE, available at www.euroscore.pil‐media.com), is used for similar purposes. The cardiac surgeon can use this information when discussing the proposed operative plan with the patient, during which an informed consent discussion detailing potential complications is essential. Data entry into software programs compatible with the STS database allows surgeons to obtain an extensive analysis of their hospital’s unadjusted and risk‐adjusted results and a comparison with national norms.
   
3. A cardiac anesthesiologist should interview and examine the patient and discuss issues related to sedation, anesthetic medications, monitoring lines, awakening from anesthesia, and mechanical ventilation. The anesthesiologist should also carefully review the patient’s medications and make recommendations (in conjunction with the surgeon’s policies) about whether certain medications should be modified or discontinued preoperatively.
   
4. Providing patients with information booklets related to their cardiac disease and proposed procedure is invaluable in alleviating some of the stress and anxiety of having to undergo cardiac surgery. If possible, nurses or physician assistants with experience in postoperative care should discuss a clinical care pathway so that the patient has a realistic expectation of what will transpire during the hospital stay. Informing the patient of what procedures will take place and when, what is expected of them on each day, when discharge should be anticipated, and what the options are for posthospital discharge care (home healthcare, rehabilitation facility, or skilled nursing facility) is extremely beneficial in enhancing the patient’s involvement in their own care and promoting a prompt recovery from surgery and early hospital discharge.

II. History

1. The nature, duration, and pattern of the patient’s cardiac symptoms should be briefly summarized to allow for symptomatic classification using either the Canadian Classification System (for angina) or the New York Heart Association (NYHA) system (for both angina and heart failure symptoms) (see Appendices IB and IC). The latter is included in the STS risk model. A careful history of medical problems and a complete “review of systems” for noncardiac issues could influence care and draw attention to issues that may need to be addressed perioperatively.
   
2. Chronic obstructive pulmonary disease (COPD) is a term often applied to patients with a significant smoking history independent of the degree of respiratory impairment. However, the degree of COPD is best defined by pulmonary function testing (PFTs). Although this is not essential in patients without functional limitations, there is a significant discrepancy between clinical symptoms and spirometric values in 30–40% of patients.^1,2 Thus, failure to perform spirometry testing may lead to underreporting of COPD and thus an underestimation of the risk of adverse outcomes in the STS database.
   
   
   
   1. The definitions of chronic lung disease in version 2.40 (2020) of the STS database specifications are as follows:
      
      
      
      1. Mild: forced expiratory volume in the first second (FEV₁) 60–75% of predicted and/or on chronic inhaled or oral bronchodilator therapy
         
      2. Moderate: FEV₁ 50–59% of predicted and/or on chronic steroid therapy
         
      3. Severe: FEV₁ <50% predicted and/or room air PO₂ <60 torr or PCO₂ >50 torr
      
      
   2. Although there are reports that the severity of COPD does not correlate with the risk of respiratory failure or mortality after coronary artery bypass grafting (CABG),^3,4 most studies have shown that patients with severe COPD have higher risks of pneumonia, prolonged ventilation, atrial fibrillation (AF), deep sternal wound infection, length of stay, and an increased operative mortality.^2,5–8 These complications may be more prevalent in elderly patients and those on steroids. Because of the association of COPD with other risk factors, such as hypertension, peripheral vascular disease (PVD), and poor left ventricular (LV) function, patients with COPD have compromised long‐term survival following CABG.³ One study found a higher, yet comparable, incidence of respiratory complications in patients with COPD after off‐pump and on‐pump coronary surgery.⁹
      
   3. The patient’s physiologic reserve and functional status, including the ability to walk up a flight of stairs or several hundred feet on a level surface, are sometimes as important, if not more important, than spirometric values in determining whether the patient can tolerate a surgical procedure. However, markedly abnormal PFTs, including an FEV₁ <0.6 or less than 50% predicted, a FEV₁/FVC ratio <70% predicted, and a diffusion capacity <50% predicted, are associated with greater morbidity and mortality after cardiac surgery.^2,4–10
      
   4. The differential diagnosis of worsening dyspnea includes both exacerbation of COPD and congestive heart failure (HF). The chest x‐ray may be helpful in differentiating between these two entities, but they are often present concomitantly. It can be difficult to quantitate the cardiac contribution to abnormal PFTs or a low diffusion capacity, especially in patients with mitral valve disease. In this situation, careful clinical judgment must be used in deciding whether surgery will improve the patient’s pulmonary status or will leave the patient a pulmonary cripple.
      
      
      
      1. B‐type natriuretic peptide (BNP) is secreted by the atria and ventricles in patients with systolic and diastolic dysfunction, with levels generally correlating with the patient’s age and ejection fraction (EF).¹¹ BNP levels are helpful in differentiating whether dyspnea is primarily of cardiac or pulmonary origin. A BNP level <100 pg/mL indicates that a patient’s dyspnea is most likely related to a primary pulmonary process, such as exacerbation of COPD. In contrast, dyspnea in a patient with a BNP level >500 pg/mL is usually caused by decompensated heart failure. Intermediate values may be associated with LV dysfunction without decompensation, but a pulmonary process must also be considered in the differential diagnosis.¹²
         
      2. An elevated preoperative BNP level (>385 pg/mL in two studies) is a predictor of postoperative LV dysfunction, the requirement for inotropic or intra‐aortic balloon pump support, and is associated with greater perioperative, one‐ and five‐year mortality after cardiac surgery.^13–16
         
      3. Some hospitals measure pro‐BNP levels, which are interpreted in a similar fashion to the BNP. Values may vary depending on the hospital’s reference range and also differ with age. A normal pro‐BNP is <125 pg/mL for patients <age 75 and <450 pg/mL for patients >age 75. Levels >450 pg/mL under age 50, >900 pg/mL for ages 50–75, and >1800 pg/mL for patients over age 75 are consistent with acute heart failure.¹⁷
      
      
   5. Baseline pulse oximetry on room air should be obtained on every patient, and if the oxygen saturation is less than 90%, arterial blood gases (ABGs) on room air should be obtained. If the patient has significant COPD or interstitial lung disease, ABGs can be valuable for comparison with postoperative values when weaning the patient from the ventilator. An elevated PCO₂ (>50 torr) is a significant marker for postoperative pulmonary morbidity and mortality. Additionally, patients on home oxygen or with a baseline PO₂ <60 torr are extremely borderline operative candidates.
      
   6. In addition to significant COPD, pulmonary complications are more common in patients who actively smoke, as they often have a productive cough or lower respiratory colonization. Other risk factors include advanced age, obesity, diabetes, preoperative cardiac instability, pulmonary hypertension, emergency surgery, and a history of cerebrovascular disease.^18–20 A logistic risk model in patients undergoing valve surgery found respiratory failure to be more common with age >70, diabetes, prior myocardial infarction (MI), congestive HF, reoperations or emergency operations, surgery for endocarditis, complex operations, and for bypass times over three hours (see Figure 10.2, p. 471).²¹
      
   7. Actively smoking patients should be advised to terminate smoking at least four weeks (and preferably two months) before surgery to decrease the volume of airway secretions and improve mucociliary transport.²² Actively smoking patients are more prone to postoperative hypoxemia, more obstructive and restrictive abnormalities in pulmonary function, more coughing that can lead to sternal dehiscence, increased fibrinogen levels and platelet aggregation leading to more thrombotic complications, and an increased risk of sternal wound infection.^20,22,23 Use of medications to assist smokers to quit, such as varenicline (Chantix) or bupropion HCL (Zyban), should be recommended as soon as possible once the patient understands the adverse influence of smoking on the perioperative course and the long‐term results of surgery. However, some patients have extreme difficulty stopping smoking due to their nicotine addiction and simply cannot stop prior to surgery. Unfortunately, not smoking for just a few days before surgery is probably of little benefit and may increase airway secretions. If a patient indicates that they have stopped smoking, further inquiry as to when this occurred is important, because being off of cigarettes for a few days (“Yes, I quit”) while hospitalized still places the patient at increased risk of pulmonary complications.
      
   8. An active pulmonary or bronchitic process (evidenced by a productive cough) should be resolved before surgery using antibiotics. Bronchospastic disease should be treated with bronchodilators and, if severe, with steroids. Pulmonary consultation may be indicated in this situation. Short‐term pulmonary rehabilitation is effective in improving perioperative pulmonary function in patients with significant COPD and can reduce the risk of pulmonary complications.²⁴
      
   9. Some patients on chronic high‐dose amiodarone therapy are prone to the development of pulmonary toxicity and adult respiratory distress syndrome (ARDS) after surgery. This is manifested by dyspnea, hypoxia, radiographic infiltrates, and a decrease in diffusion capacity. This problem carries a very high mortality rate.²⁵ Evidence of preoperative pulmonary toxicity with a decrease in diffusion capacity may contraindicate a cardiac surgical procedure. Avoidance of potential contributing causes, such as a high inspired oxygen fraction, long duration of bypass, and fluid overload, is critical. On rare occasions, this syndrome may occur after a very short course of amiodarone, and it appears to be an idiosyncratic or hypersensitivity reaction.²⁶ Although baseline PFTs are not necessary in patients on a short‐term course of amiodarone for AF prophylaxis, they should be considered when it is anticipated that the amiodarone may be given for more than one month (e.g. after a Maze procedure).
   
   
3. A history of heavy alcohol abuse identifies potential problems with intraoperative bleeding and postoperative hepatic dysfunction, agitation, and alcohol withdrawal. Prevention of postoperative delirium tremens (DTs) with thiamine, folate, and benzodiazepines should be considered. Bioprosthetic valves should be selected to avoid postoperative anticoagulation.
   
   
   
   1. Mildly elevated liver function tests (LFTs) are often of unclear significance and usually do not require further evaluation. However, in a patient with a drinking history, this does not exclude the possibility of alcoholic hepatitis or cirrhosis, and a gastrointestinal (GI) consultation may be indicated. A common cause of mildly elevated LFTs is use of a statin medication for dyslipidemia. Patients with nonalcoholic steatohepatitis (NASH) can also develop cirrhosis that should be evaluated in a similar fashion.
      
   2. A history of GI bleeding, an elevated prothrombin time (reported as the INR), a low serum albumin indicating impaired synthetic function or malnutrition, an elevated bilirubin, or a low platelet count may suggest the presence of severe cirrhosis with portal hypertension and/or hypersplenism. A liver biopsy may be indicated to evaluate the risk of surgery and the potential for postoperative hepatic failure. If surgery is performed in a patient with esophageal varices, transesophageal echocardiography should probably be avoided.
      
   3. Two risk models that have been used in cirrhotic patients to predict outcomes are the Child‐Turcotte‐Pugh (CTP) and the Mayo End‐Stage Liver Disease (MELD) scores. Patients with CTP class A cirrhosis (Table 3.2) will usually tolerate cardiopulmonary bypass (CPB), but may have a higher risk of postoperative complications, including infections due to immune dysfunction and poor nutritional status, bleeding from impaired coagulation factor synthesis and thrombocytopenia, GI complications, and respiratory, renal, and hepatic failure.²⁷ Risk factors for mortality in patients with cirrhosis include older age, higher bilirubin levels, high central venous pressures, ascites, emergency surgery, prolonged CPB time, and perioperative thrombocytopenia.^27,28
      
   4. Patients with advanced alcoholic cirrhosis (class C) or a CTP score ≥8 are generally not candidates for cardiac surgery. The operative mortality rate for patients with cirrhosis in general is very high, with a literature review in 2015 reporting that the average operative mortality after cardiac surgery was 9% for class A, 37.7% for class B, and 52% for class C cirrhosis.²⁹ Furthermore, the one‐year mortality rates were also very high at 27.2, 66.2, and 78.9%, respectively. Nonetheless, there are isolated small series showing better survival rates. One study from Taiwan reported an overall operative mortality of 16%, and even though only 9% of the patients were CTP class C, mortality did not correlate with CTP or MELD class.³⁰
      
   5. The MELD score includes both hepatic and renal variables and is considered a more sensitive indicator of surgical risk.²⁸ It is calculated from a summation of multiples of natural logarithms of the INR, serum creatinine, and total bilirubin (see calculator at www.mayoclinic.org/meld). A surgical mortality risk of 50% for a MELD score ≥15 was noted in one study,³¹ and a mortality risk of 56% for a score exceeding >13.5 was reported in another, which also noted only a 23.8% one‐year survival in these patients.²⁸ An additional ominous sign is an associated platelet count of less than 96,000/μL (reflecting advanced liver fibrosis).³²
      
   6. With recognition that CPB is a major contributing factor to adverse outcomes, off‐pump surgery should be considered in patients with advanced liver disease if their lifestyle and lifespan are compromised primarily by their heart disease.³³

4. Diabetes mellitus is a condition associated with extensive and diffuse atherosclerotic disease due to metabolic derangements and a proinflammatory and prothrombotic state.³⁴ It may range in severity from mild hyperglycemia controlled with diet or oral medications to more severe diabetes requiring insulin. The more severe and uncontrolled the diabetes, the greater the risk of obesity, congestive HF, PVD, extensive coronary artery disease (CAD), and chronic kidney disease.³⁵ Nonetheless, the long‐term prognosis in diabetics with multivessel disease is improved with surgery.^36,37
   
   
   
   1. Generally, diabetes is associated with an increased postoperative risk of stroke, infection, renal dysfunction, and operative mortality, even after off‐pump surgery.^35,38 A decrease in saphenous vein graft patency (hence the desire to use more arterial grafts) and a worse long‐term survival have also been noted.³⁹ Noninsulin‐dependent diabetics tend to fare somewhat better, with a lower immediate risk of postoperative complications, including respiratory and renal failure and mediastinitis. Their long‐term prognosis is favorable in the absence of significant comorbidities.^34,37
      
   2. An elevated hemoglobin A1c (HbA1c) >7% is a marker for poorly controlled diabetes in the previous 3–4 months and has been associated with more adverse outcomes, including sternal wound infection, stroke, renal failure, and MI, as well as reduced long‐term survival after CABG.^40–43 One study showed that the CABG mortality risk increased fourfold when the HbA1c was >8.6%.⁴⁴
      
   3. To optimize perioperative care, careful attention to potential diabetic‐related complications is essential.
      
      
      
      1. Any preexisting infections must be treated (urinary infections are particularly common in diabetic women).
         
      2. The STS guidelines recommend that oral hypoglycemics should be withheld for 24 hours prior to surgery and insulin should not be used after an evening meal the night before surgery.^45,46 Monitoring of intraoperative glucose levels and aggressive treatment to maintain blood glucose in the 120–180 mg/dL range is essential to reduce neurologic morbidity and the risk of infection.⁴⁶ Interestingly, a literature review suggested that patients with perioperative hyperglycemia, even if not diabetic, had worse outcomes, with twice the mortality at one year compared with normoglycemic patients; however, patients with well‐controlled diabetes may have comparable outcomes to those without diabetes with similar glycemic control.⁴⁷
         
      3. In diabetic patients with any element of chronic kidney disease, steps must be taken during cardiac catheterization and surgery to optimize renal function (see Chapter 12).
         
      4. The long‐term results of CABG in diabetics are improved with use of bilateral internal thoracic arteries (BITA) or radial artery grafts, since saphenous vein graft patency is compromised in diabetics. Despite multiple reports indicating an association between BITA use and the increased risk of deep sternal wound infections, especially in obese diabetic woman, other reports suggest that this is not the case with meticulous skeletonized ITA harvesting.^48–52 Notably, diabetics may be more prone to phrenic nerve dysfunction after ITA harvesting, so cauterizing near the phrenic nerve must be avoided.⁵³
         
      5. Although most patients are currently managed with glargine insulin (Lantus), which has improved efficacy and safety outcomes compared with NPH insulin,⁵⁴ the few patients currently taking NPH insulin are at increased risk of experiencing an allergic reaction to protamine.⁵⁵
         
      6. Management of postoperative hyperglycemia with a defined protocol (see Appendix 6) is an essential element of perioperative care and has been shown to reduce operative morbidity and mortality.⁴⁵ An endocrine consultation may be helpful in patients with refractory hyperglycemia.
   
   
5. Neurologic symptoms, whether active (transient ischemic attack [TIA]) or remote (history of a stroke), increase the risk of perioperative stroke and warrant evaluation.^56,57 Approximately 10–15% of patients requiring CABG have significant carotid disease. Selective screening limited to patients >age 65, or those with carotid bruits, TIA, or stroke can identify most patients at high risk.⁵⁸ Patients with hypertension, PVD, and particularly women with left main disease or calcified aortas are also at higher risk and should be screened.⁵⁹
   
   
   
   1. Generally, a carotid noninvasive study with ultrasound imaging and measurement of flow velocities should be performed in the patient with neurologic symptoms, a history of a carotid endarterectomy (CEA), or asymptomatic carotid bruits to assess for significant stenoses or flow‐limiting lesions. A peak systolic velocity (PSV) >230 cm/s in the internal carotid artery (ICA), an ICA/common carotid artery PSV >4.0 cm/s, or an end‐diastolic velocity >100 cm/s associated with significant plaque burden by ultrasonic imaging is consistent with significant stenosis. Further evaluation by carotid arteriography (usually magnetic resonance angiography) may be considered if noninvasive studies are inconclusive or a more precise visualization of the carotid vessels is desired.
      
   2. Actively symptomatic carotid disease always warrants CEA either prior to or at the time of cardiac surgery. A combined CABG–CEA should be performed in the patient with unstable angina or significant myocardium at risk if neurologic symptoms are present.
      
   3. The management of asymptomatic carotid lesions in patients requiring cardiac surgery is controversial and is noted in the discussion of carotid bruits (see section III.D, pages 184–185).
   
   
6. A history of saphenous vein stripping and/or ligation or distal vascular reconstructive procedures using saphenous vein alerts the surgeon to potential problems obtaining satisfactory conduit for bypass grafting.
   
   
   
   1. Noninvasive venous mapping of the lower extremities may identify satisfactory greater or lesser saphenous veins for use, but it is not always reliable.⁶⁰ Consideration should be given to whether bilateral ITAs can be used to reach the surgical targets or whether their use is contraindicated (morbidly obese and diabetic females in particular).
      
   2. Doppler assessment of the palmar arch or digital plethysmography with radial compression can be performed to assess the feasibility of using the radial artery as a bypass conduit (i.e. confirming that the arm is ulnar‐dominant). Contraindications may also include Raynaud’s disease, radial dominance, and possibly prior radial artery catheterization. Informing the patient of potential complications of radial artery harvesting, specifically numbness of the dorsum of the thumb and part of the thenar eminence or thumb weakness from trauma to the superficial radial nerve, is essential, as it may occur in 30–35% of patients.^61,62 An increased incidence of forearm neurologic deficits has been noted in smokers, older patients, and those with diabetes, obesity, and PVD.^63,64
      
   3. Venipunctures and intravenous (IV) catheters should be avoided in the arm from which the radial artery will be harvested. The anesthesiologist should also be alerted to avoid placing a radial artery line or IV catheter in that arm for the surgical procedure.
   
   
7. Urologic symptoms suggest the presence of an active urinary tract infection (UTI) that must be treated before surgery. In men, a history of prostatic cancer treated by irradiation, a prior transurethral resection, or other urinary symptoms consistent with prostatic hypertrophy identify potential problems with Foley catheter placement in the operating room. Use of a coudé catheter may be necessary. Urologic consultation should be obtained if a catheter cannot be passed. Either a catheter may be placed after dilating the urethra or a suprapubic tube may be inserted. Prolonged postoperative urinary drainage should be anticipated until the patient is fully ambulatory or until further urologic evaluation has been performed.
   
8. A history of significant ulcer disease or GI bleeding may necessitate further evaluation by endoscopy, especially if the patient will require postoperative anticoagulation. However, invasive diagnostic tests may need to be deferred in patients with significant coronary disease. Use of postoperative proton pump inhibitors (PPIs) should be considered in these patients, but whether stress prophylaxis should be used routinely or even in ICU patients considered at high risk for GI bleeding remains controverisal.^65–67 Gastric acid suppression with PPIs or histamine antagonists may be beneficial in reducing the risk of stress ulceration, but their use is associated with an increased risk of pneumonia. This risk is minimized with the use of sucralfate, which, however, has not been shown to reduce the risk of GI bleeding in critically ill patients.⁶⁸ Nonetheless, sucralfate is commonly given routinely, and PPIs should be considered in patients receiving dual antiplatelet therapy or receiving one antiplatelet drug with additional risk factors for bleeding.⁶⁶
   
9. The risk of infection is increased if another infectious source is present in the body (commonly a urinary tract or skin infection). Concurrent infections must be identified and treated before surgery. An upper respiratory infection may increase the risk of pulmonary complications, and bacterial infections may increase the risk of a hematogenous sternal wound infection and can seed a prosthetic heart valve. To reduce the risk of methicillin‐resistant Staphylococcus aureus (MRSA) infections, prophylaxis with nasal mupirocin can be universally recommended unless a preliminary nasal swab is negative.^69,70
   
10. The patient’s medications should be reviewed to determine which ones to continue up to the time of surgery and which ones to stop in advance or not take the morning of surgery (see section IV, starting on page 186, and section VII, pages 198–199). Patients on chronic steroid therapy should receive a stress dose of hydrocortisone 100 mg IV at the beginning of surgery and should be given a few doses afterwards as well.
    
11. The patient’s allergies must be carefully reviewed and listed in the medical record. Commonly, an adverse reaction is considered an allergy to the patient, but it does alert the healthcare team to medications that are best avoided after surgery to minimize side effects. Alternative antibiotic prophylaxis may be required for true antibiotic allergies. Just the mention of a potential latex allergy should be brought to the attention of the operating room to avoid any latex‐containing products (including gloves, urinary catheters, Swan‐Ganz catheters, and tourniquets used during surgery).
    
12. Other significant past medical history, such as prior chest irradiation for cancer (usually for mediastinal lymphoma, breast, or lung cancer) or a psychiatric history, should be detailed in the medical record. A thorough review of systems should be able to identify other comorbid conditions likely to affect the outcome of surgery.

III. Physical Examination

1. The patient’s general appearance, mental status, and affect should be evaluated and noted in the medical record as a baseline for comparison with the postoperative period. Prior to transcatheter procedures, a mini‐mental examination is performed as part of “frailty” testing.
   
2. An active skin infection or rash that might be secondarily infected must be treated before surgery to minimize the risk of sternal wound infection.
   
3. Dental caries must be treated before operations during which prosthetic material (valves, grafts) will be placed.^71,72 Dental extractions, however, should be recommended cautiously in patients with severe ischemic heart disease or critical aortic stenosis. Cardiac complications may occur even if dental procedures are performed under local anesthesia. A report from the Mayo Clinic found that 3% of patients died within 30 days of dental work done in anticipation of surgery.⁷³
   
4. Carotid bruits are a marker of carotid disease, which is present in about 10–15% of patients with significant coronary disease. Carotid noninvasive studies are warranted in virtually all patients with bruits to assess for high‐grade unilateral or bilateral disease because of the association of severe carotid disease with postoperative stroke, which is associated with significant mortality.^74,75
   
   
   
   1. The management of the patient with an asymptomatic carotid lesion requiring open‐heart surgery is controversial. A meta‐analysis from 1999 suggested that a combined CEA–CABG had a higher death or stroke rate than a staged approach.⁷⁶ However, another meta‐analysis from 2014 showed equivalent results between the two approaches.⁷⁷ Another study showed equivalent results between a staged carotid stenting–CABG approach and a combined CEA–CABG, with both having lower MI rates than a staged CEA–CABG approach.⁷⁸ These studies suggest that combined approaches are noninferior to staged approaches, but, for the latter, there must not be too much of a delay before the second procedure (the CABG) to prevent cardiac events in the interim.
      
   2. Because carotid disease is a marker for aortic atherosclerosis, it is not surprising that stroke risk is greater in patients with aortic calcification or atherosclerosis, likely explaining why half of perioperative strokes following combined operations occur contralateral to the operated side.⁷⁹
      
   3. If the patient presents with an acute coronary syndrome or has a large degree of myocardium at risk, most surgeons would consider performing a combined CABG–CEA for a unilateral carotid stenosis >90%. In contrast, preliminary CEA or stenting would be the preferred approach in patients with stable angina and might result in a lower overall risk of stroke, MI, and death. For patients requiring emergency CABG, that procedure alone is indicated, accepting the slightly increased risk of stroke with known carotid disease.
      
   4. The risk of stroke with bilateral disease (>75% bilaterally) is significant during isolated CABG (as high as 10–15% in one report), especially in patients with unilateral stenosis with contralateral occlusion.⁷⁴ However, it remains quite significant even with a combined operation. Thus, the operations should be staged with the CEA performed first if cardiac disease permits. If this is not possible because of unstable angina, left main or severe three‐vessel disease with a large amount of “myocardium in jeopardy”, preliminary carotid stenting or a combined operation should be performed, with the understanding that the risk of stroke is somewhat increased.
   
   
5. Bilateral arm blood pressures should be measured. A differential systolic blood pressure of >10 mm Hg may identify significant subclavian artery stenosis, which is a relative contraindication to the use of a pedicled ITA graft.⁸⁰ This finding is also noted in some patients presenting with a type A aortic dissection.
   
6. The presence of a heart murmur warrants a preoperative echocardiogram if no valvular abnormality had been identified at the time of catheterization. Occasionally, new‐onset ischemic mitral regurgitation or unsuspected aortic valve disease will be detected. In terms of valve selection, risk assessment, and informed consent, it is certainly preferable that the need for an additional valve procedure be recognized before surgery, rather than being identified for the first time in the operating room.
   
7. An abdominal aortic aneurysm detected upon palpation should be evaluated by ultrasound. IABP placement through the femoral artery should be avoided to prevent distal atheroembolism. Further evaluation by CT scanning is warranted before considering femoral artery cannulation for a minimally invasive procedure.
   
8. Severe peripheral vascular disease (PVD) must be assessed by a careful pulse examination. It is often associated with cerebrovascular disease and may prompt a preoperative carotid noninvasive study.⁵⁹ PVD adversely affects long‐term survival after cardiac surgery, but it is not predictive of operative mortality, although it is included in the STS risk calculator.^81–83 Weak femoral pulses may be indicative of “inflow” aortoiliac disease. If the ascending aorta is also significantly diseased and an alternative cannulation site must be utilized for CPB, the axillary artery should be considered.⁸⁴
   
   
   
   1. Aortoiliac disease may dictate the unsuitability of the femoral arteries for cannulation, especially for minimally invasive valve surgery, or for placement of an IABP. An abdominal pelvic CT scan to assess the iliofemoral system may dictate whether percutaneous femoral cannulation is feasible or whether it runs the risk of a retrograde dissection or even retrograde embolization of atherosclerotic debris to the brain on CPB.
      
   2. Abdominal‐pelvic CT scanning is an essential component of the work‐up for transcatheter aortic valve replacements (TAVRs). Vessel tortuosity, calcification, and size need to be assessed to determine whether a transfemoral or alternate access approach is indicated.
      
   3. PVD may contribute to poor leg wound healing after saphenous vein harvesting, although this is generally not a significant problem with endoscopic vein harvesting. If there are plans for future peripheral vascular reconstruction, the vein should be harvested from the opposite leg.
   
   
9. The presence of varicose veins or a history of deep venous thrombosis (DVT) identifies potential problems with conduits for CABG. The distribution of varicosities may indicate whether or not the greater saphenous vein is involved. Noninvasive venous mapping may identify a normal greater saphenous vein despite significant varicosities.⁶⁰ The lesser saphenous vein distribution should be inspected to determine whether it might serve as a potential conduit. Assessment of the radial artery, as noted in section II.F, should be considered. BITA grafting may be required, so patients considered at increased risk for a sternal infection should be so informed.

IV. Adjustment of Medications Prior to Cardiac Surgery

Review of the patient’s prior and current medications is important. Particular attention should be paid to antiplatelet/anticoagulant medications, which should be either continued or stopped prior to surgery, depending on the clinical situation (Tables 3.3 and 3.4).

1. Aspirin (ASA) is commonly taken by patients with known ischemic heart disease and is given routinely to patients presenting with an acute coronary syndrome (ACS). Preoperative use of aspirin is considered beneficial in reducing perioperative infarction and operative mortality, and improving graft patency and the outcomes of CABG.^85–90 However, although this was documented in several meta‐analyses, a trial published by one of the same authors failed to confirm these benefits.⁸⁸ Aspirin irreversibly acetylates platelet cyclooxygenase, impairing thromboxane A₂ formation and inhibiting platelet aggregation for the lifespan of the platelet (7–10 days). Thus, aspirin will be superimposing impaired platelet dysfunction on the clotting derangements induced by CPB.
   
   
   
   1. Although the preoperative use of aspirin increases perioperative blood loss, this is generally noted in patients taking doses higher than 81 mg daily. Therefore, it is recommended to continue aspirin 81 mg daily up to the day of surgery in most patients undergoing CABG.^87,89,90 In patients undergoing other forms of open‐heart surgery, stopping aspirin 3–5 days in advance should be sufficient to allow for significant regeneration of the platelet pool to minimize its antiplatelet effects.
      
   2. Patient response to the antiplatelet effects of aspirin is quite variable. Some patients are somewhat resistant (often from using enteric‐coated aspirin), and others have prominent platelet inhibition. A variety of platelet aggregometry tests are available to assess the antiplatelet effect of aspirin, but they do not necessarily correlate with the degree of platelet inhibition, and are rarely indicated before surgery.⁹¹ Patients taking higher doses of aspirin and those with conditions associated with platelet dysfunction, such as uremia and von Willebrand’s disease, may also exhibit more bleeding. If these patients are recognized, it may be advisable to stop aspirin a few days before surgery.
      
   3. Studies have shown that there is enhanced platelet aggregation and thromboxane formation in the early postoperative period, even in patients receiving preoperative aspirin.⁹² Thus, patients with aspirin resistance will have greater platelet reactivity, which is associated with an increased risk of graft thrombosis.⁹³ Although various studies provide conflicting data on whether platelet activation is greater following on‐ or off‐pump (OPCAB) surgery,^94,95 routine use of preoperative aspirin and initiation of aspirin within 6–8 hours after surgery should mitigate the extent of platelet activation and aggregation to some degree, most likely accounting for the improved graft patency, lower rate of perioperative MI, and improved operative survival after both types of surgery.^93,96

2. The P2Y12 inhibitors are thienopyridines that inhibit platelet function by irreversibly modifying the platelet adenosine diphosphate (ADP) receptor P2Y12, which then inhibits ADP‐mediated activation of the glycoprotein IIb/IIIa receptor. This results in inhibition of platelet activation and aggregation. These medications are given along with aspirin for one month for patients receiving bare‐metal stents and for 6–12 months for patients with drug‐eluting stents to minimize the risk of stent thrombosis.⁹⁷ However, many patients are maintained on them indefinitely after PCI. They are also given to patients presenting with acute coronary syndromes and to those in whom PCI is contemplated, whether elective or not.
   
   
   
   1. Clopidogrel is biotransformed through a two‐step process into an active metabolite which produces its antiplatelet effects. Genetic polymorphisms in the CYP2C19 allele reduce this conversion, resulting in clopidogrel resistance. Prior to PCI, a 300–600 mg load is given, which achieves about 40% platelet inhibition within a few hours, followed by 75 mg daily. Despite a half‐life of about seven hours, the antiplatelet effect lasts for the lifespan of the platelet, so cessation for five days prior to surgery is recommended in elective situations.⁸⁹
      
   2. Ticagrelor is a reversible noncompetitive inhibitor of the P2Y12 receptor that has a more rapid onset of action and more pronounced inhibition of platelet function than clopidogrel. Ticagrelor and its metabolite are both pharmacologically active with a peak effect in 1.5 hours after a 180 mg load, which is then followed by 90 mg twice a day. It is more effective than clopidogrel in reducing death in patients with an ACS with a comparable rate (12%) of major bleeding. It has a reversible effect on platelet function with a half‐life of 7–8 hours, with 80% recovery of platelet function by 72 hours.⁹⁸ This suggests that surgery can be safely performed if ticagrelor has been withheld for 72 hours, although it is still recommended that it be stopped five days prior to surgery.⁸⁹
      
   3. Prasugrel is a prodrug that is converted to an active metabolite which produces irreversible antagonism of the P2Y12 receptor. It is approximately 10 times more potent than clopidogrel and produces more rapid onset of action with 50% inhibition within one hour. The maximum platelet inhibition is 80%. Although clinically superior to clopidogrel in ACS patients undergoing PCI, it may be associated with a higher risk of bleeding and it is not recommended in patients >age 75 or patients with a history of TIAs or stroke. Despite a comparable half‐life of seven hours, the irreversible effect on platelet function mandates that it be stopped at least seven days before surgery.⁸⁹
      
   4. Cangrelor is an intravenous reversible inhibitor of P2Y12 which produces nearly 100% platelet inhibition with a rapid onset of action within minutes since it does not require conversion to an active metabolite. It has a half‐life of 3–6 minutes with reversal of effect in 1–2 hours.⁹⁹
      
   5. The risks of perioperative bleeding, need for transfusions, and re‐exploration for bleeding are unequivocally increased when patients have received a P2Y12 inhibitor within several days of surgery.¹⁰⁰ This has led to the recommendation that surgery be delayed 5–7 days following cessation of these drugs.⁸⁹ However, bleeding is more related to the patient’s responsiveness to these medications (primarily clopidogrel) than to the timing of discontinuation.¹⁰¹ Use of platelet function testing can determine the patient’s sensitivity to the P2Y12 inhibitor. If platelet inhibition (platelet reactive units, or PRUs) is <30%, surgery can be safely performed without an increased bleeding risk.¹⁰²
      
      
      
      1. Emergency surgery is indicated for patients with a STEMI or other ACS presentation with refractory ischemia when PCI is not feasible. It is associated with the highest bleeding risk, especially since platelet transfusions given within six hours of a loading dose or four hours after a maintenance dose of a P2Y12 may be less effective because some of the active metabolite may bind exogenous platelets.
         
      2. Urgent surgery for patients with critical anatomy should usually be performed within a week of catheterization, when antiplatelet effects may not have completely dissipated. Timing of surgery balances the risk of an ischemic event versus the risk of bleeding requiring platelet transfusions. Clearly, surgery should never be delayed if clinically indicated. Use of platelet testing is invaluable in assessing when the risk of bleeding has lessened and surgery can be performed with a lower bleeding risk.
         
      3. Some patients require cardiac surgery despite having received a recent stent. For example, a patient with a STEMI may be found to have multivessel disease, but the culprit lesion may be stented to promptly reperfuse the potential infarct zone, and urgent surgery is then recommended to address the other lesions. Another example is the patient with recurrent chest pain within a few months of receiving a drug‐eluting stent. Stopping a P2Y12 inhibitor for one week prior to surgery will increase the risk of stent thrombosis, so two feasible approaches, other than operating without stopping the P2Y12 inhibitor, are to (1) stop the medication for three days, continue aspirin, and operate with mild residual antiplatelet activity or, preferably, (2) stop the P2Y12 inhibitor five days prior to surgery, continue aspirin, and admit the patient for a glycoprotein IIb/IIIa inhibitor for a few days, and stop that four hours prior to surgery. Following the operation, the P2Y12 inhibitor is restarted as soon as possible with a loading dose.¹⁰³
         
      4. It has been suggested that use of an antifibrinolytic medication, such as tranexamic acid, can mitigate some of the bleeding noted in patients in whom a P2Y12 inhibitor was not stopped prior to surgery.¹⁰⁴
   
   
3. Heparin is given to patients with an ACS before and after cardiac catheterization if urgent surgery is recommended. It is also used in patients in whom an IABP is placed preoperatively. It may also be used as a bridge to surgery in patients taking preoperative warfarin.
   
   
   
   1. Unfractionated heparin (UFH) is given using a weight‐based protocol (see Appendix 7) and requires monitoring by a partial thromboplastin time (PTT) to ensure a therapeutic range of approximately 50–60 seconds. Heparin is usually stopped about four hours before surgery. However, in patients with critical CAD, it is best to continue heparin into the operating room. This should not pose a significant risk during the insertion of central lines. When heparin is given for several days, the platelet count should be checked on a daily basis to assess for the development of heparin‐induced thrombocytopenia (HIT) (see pages 251–253).
      
   2. Low‐molecular‐weight heparin (LMWH) (enoxaparin) binds to antithrombin, which then accelerates inhibition of activated factor Xa, with minimal inhibition of thrombin (factor IIa). It is commonly used in patients with an ACS (1 mg/kg SC twice a day) due to its efficacy and simplicity of use, with no requirement for blood monitoring. It may also be used as an alternative to UFH during cardiac catheterization procedures. It is commonly used for venous thromboembolism (VTE) prophylaxis in hospitalized patients at a dose of 40 mg SC once daily. Studies have reported an increased risk of perioperative bleeding in patients on LMWH.¹⁰⁵ It has an elimination half‐life of 4–5 hours and exhibits 30% of anti‐factor Xa activity at 12 hours. It is recommended that the last dose should be given five half‐lives or approximately 24 hours prior to surgery to minimize perioperative bleeding. Only 60% of LMWH can be neutralized by protamine, although its effect can be reversed by platelet factor 4.¹⁰⁶
   
   
4. Warfarin is given primarily to patients with mechanical prosthetic valves, AF, a history of DVT or pulmonary embolism (PE), or hypercoagulable disorders. Warfarin should be stopped five days prior to surgery and the INR should be rechecked within 24 hours before the procedure. Bridging anticoagulation is not necessary in low‐risk patients.^107,108
   
   
   
   1. Patients at high risk for a clinical event should be bridged to surgery with either UFH or LMWH. For outpatients, LMWH (enoxaparin 1 mg/kg SC) is usually given for 2–3 days, starting when the INR is below therapeutic range (usually two days after stopping warfarin) and should be discontinued 24 hours prior to surgery. Since there will still be some residual anticoagulant effect after it is stopped, admission for UFH for a few hours prior to surgery is not necessary. Inpatients may receive UFH, which is then stopped four hours prior to surgery. High‐risk patients include those with the following:¹⁰⁸
      
      
      
      1. Mechanical mitral valve replacement
         
      2. Mechanical aortic valve replacement with any thromboembolic risk factor (e.g. AF, prior thromboembolism, hypercoagulable condition, non‐bileaflet valve, LV systolic dysfunction, or >1 mechanical valve).
         
      3. AF at high risk for embolic stroke (CHA₂DS₂‐VASc score ≥5, stroke or systemic embolism within three months, associated rheumatic mitral stenosis)
         
      4. VTE within the preceding three months
         
      5. History of prior thromboembolism during interruption of anticoagulation
      
      
   2. If the patient requires urgent surgery and has an elevated INR, administration of 5 mg of vitamin K given PO should reduce the INR within 12–24 hours. IV vitamin K given intravenously over 30 minutes is more expeditious in reversing the INR, but it runs the risk of an anaphylactic reaction. Subcutaneous vitamin K has unpredictable and delayed absorption and is not recommended. Fresh frozen plasma may be necessary if more emergent surgery is indicated and prothrombin complex concentrate (PCC [Kcentra]) in a dose of 500 units of factor IX (usually 25–50 units/kg) may also be considered for rapid reversal.¹⁰⁹
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