Coronary Artery Bypass Grafting

The most common indication for cardiac surgery is coronary artery disease. More than 50% of patients undergoing coronary artery bypass grafting (CABG) are >= 65. These elderly patients tend to be sicker than younger patients undergoing this procedure; they are more likely to have unstable angina, a history of heart failure, high-risk coronary artery disease (eg, left main coronary artery stenosis, triple vessel disease), left ventricular dysfunction, and a greater number of coexisting noncardiac disorders. In addition, the proportion of women vs. men who undergo CABG is greater in elderly than in younger populations.

The technique for CABG is similar in younger and elderly patients. Friable tissues, abnormalities of the ascending aorta due to age, severe calcific atherosclerosis, or all three may complicate arterial cannulation or proximal anastomoses. Intraoperative epicardial or transesophageal echocardiography appears to minimize procedural difficulties and help reduce the risk of atheroembolism, which is a problem in the elderly.

Prognosis

Between 1969 and 1998, mortality rates among elderly patients varied widely from 0 to 21%, probably because patient selection criteria differed, rates increased with age, and results improved over time because of advances in treatment. Overall perioperative mortality rates continue to improve but are still higher for elderly patients than for younger patients. Rates are also higher for those needing urgent or emergency surgery. In addition, perioperative mortality rates are higher for women than for men. Additional predictors of increased mortality are shown in Table 96-1.

Increased morbidity leads to longer hospital stays; as a result, the duration of hospitalization increases with age. Stroke, supraventricular arrhythmias, transient psychoses, heart block, pulmonary embolism, postoperative bleeding, respiratory distress, and renal failure occur more frequently in elderly persons than in younger persons. The elderly also have a higher incidence of postoperative psychoses than do younger patients. They also have a tendency toward reduced mobility, requiring that particular attention be given to chest physiotherapy and wound care, especially in patients > 80. However, the absolute duration of hospitalization has declined for all age groups in recent years, and many elderly patients can be rapidly discharged.

The 5-year postoperative survival rate is generally > 80% for patients > 65; the 10-year postoperative survival rate is about 80% for patients < 65 and 65% for those 65 to 74. The 8-year postoperative survival rate is about 55% for patients >= 75; however, data are limited. Preoperative left ventricular dysfunction and coexisting disorders strongly affect long-term survival: The 10-year postoperative survival rate is substantially worse for patients >= 65 with left ventricular dysfunction than for those with normal left ventricular function.

The 6-year survival rate is better for elderly angina patients treated surgically than for those treated medically, and relief of chest pain is significantly greater for those treated surgically. Among octogenarians, the 3-year survival rate is also better for those treated surgically than for those treated medically. However, the oldest patients who undergo CABG tend to be a select population, which may partially explain this improved outcome. Functional outcome improves significantly only in patients treated surgically. However, among lower-risk elderly patients with mild stable angina but with well-preserved left ventricular function and no left main coronary artery disease, survival rates do not differ between those treated surgically and those treated medically.

Functional outcomes in elderly patients who undergo CABG are generally good. Surgery relieves angina in the elderly equally or possibly more effectively than in younger patients, possibly because levels of physical activity among the elderly are reduced. Postoperative mental health function and health-related quality-of-life measurements appear to be better in patients >= 65 than in those < 65. Typically, patients > 70 improve an average of about 1.5 New York Heart Association functional classes. Across all age groups, the symptomatic benefits of CABG tend to be better in men; angina recurs more often in women.

Preoperative Assessment

The severity of angina should be clinically determined; assessing its effect on quality of life may be complicated in the elderly by vagaries of memory, by the masking of symptoms through reduced physical activity, by the occurrence of anginal equivalents (eg, dyspnea, abdominal pain, syncope), and by the presence of coexisting disorders that mimic angina (eg, cervical spine disease, diaphragmatic hernias). Ischemia-induced heart failure and ventricular arrhythmias may also warrant coronary revascularization.

Understanding the patient's desires, motivation, and lifestyle is also important when deciding whether to perform CABG. In this regard, determination of physiologic age as opposed to chronologic age may be helpful. Close attention to coexisting noncardiac disorders is essential. The medical and social histories, physical examination, and routine laboratory tests should provide most of the necessary information.

The efficacy and acceptability of drug therapy must be assessed, because drug-related problems are common in elderly patients. Angiography is needed to assess the potential for adequate revascularization. The presence and severity of left ventricular dysfunction and other cardiac conditions (eg, aortic stenosis, conduction disease) are also important factors to consider when planning therapy.

Postoperative Treatment

In the postoperative intensive care unit, physiologic monitoring and respiratory support may need to be prolonged; thus, the prevention of sepsis is a major goal. Gradual, but steady, resumption of normal activity, mobility, and independence is also a major goal of postoperative treatment.