See Table 8.1. Coronary artery bypass graft (CABG) surgery in the modern era is routine, although it remains a major invasive procedure. However, the spectrum of cases presenting for coronary surgery becomes evermore complex, older, and with more comorbidities, influencing risk. Coronary arterial disease is a vascular disease, which is a generalized process, and patients presenting for CABG surgery are a high-risk group for multiple other complications. The risk of major complications is largely determined by the severity of the cardiac ischemic insult and comorbidities existing prior to surgery. Early major complications include death, bleeding, cardiac arrythmias, and wound infections. Chest infection is relatively common and is reduced by early mobilization and physiotherapy. Later, debilitating complications include sternal osteomyelitis and chronic pain, which are relatively rare but may be serious. Other major complications include respiratory, renal, and multiorgan failure, which may cause severe disability and prolong hospital stay, and are a significant cause of mortality. Postoperative instability of anticoagulation is relatively common, and bleeding from any site may result, but is rarely severe. Bleeding into the brain or gut may occur and can be catastrophic. Stroke may be embolic or associated with postoperative coagulopathy and is an early cause of mortality or serious permanent disability. Perioperative myocardial infarction may occur, as the underlying problem is coronary arterial insufficiency. The risks of CABG surgery have to be balanced against the risks of not performing the surgery, which may be considerable. CABG surgery is essentially palliative, and redo-CABG surgery is occasionally necessary, due to deterioration of the graft or progressive native coronary arterial disease. Other complications include discomfort, chronic pain, pulmonary embolism, and restenosis. Emergency operations carry higher risk than elective surgery. Carotid endarterectomy may need to precede CABG for high-grade carotid stenosis, to reduce stroke risk. Erosion of sternal wires through skin or dehiscence is alarming for the patient, although a relatively rare problem. Keloid scar formation may be severe, irritating, and unsightly. Insertion of pleural drain tubes is almost uniform.

Stroke, myocardial infarction, pulmonary embolus, pneumonia, intrathoracic bleeding, and severe arrhythmias represent serious complications which are fortunately rare but can be fatal or debilitating. Altered mental function, DVT, infection, chronic pain, anticoagulation instability, reoperation, and sternal osteomyelitis are usually less life-threatening but often severely debilitating complications. Reoperation may be required acutely (<7 days) most often due to bleeding or recurrent ischemia or chronically (>2 months) due to pericardial effusion, both being serious complications associated with increased morbidity and mortality. Multisystem organ failure prolongs ICU care and is the usual prodrome to death associated with complications of CABG, often related to underlying comorbidity. Acute renal failure may require dialysis and is associated with up to 50 % mortality. Respiratory failure may require prolonged mechanical ventilation. Wound infection, sternal osteomyelitis, mediastinitis, and lung infection are uncommon but can be serious complications. Gastrointestinal complications are rare and, when they arise, are often devastating. They may be severe including ulceration, bleeding, bowel ischemia, biliary colic/stasis, pseudo-obstruction/ileus, and pancreatitis. Mortality risk is increased (with or without operation) by existing preoperative conditions, such as diabetes, renal failure, cardiac failure, aortic disease, lung disease, advanced age, and recent smoking history. Significant risk of severe complications may occur without any surgery. Increased use of percutaneous revascularization methods may select out an older more complex population for CABG surgery, which may effectively increase the risk of complications, including mortality.