Next to operative mortality, permanent stroke is the most dreaded complication of myocardial revascularization, not only because of the potential devastating consequences to the patient but also because of the increased cost of hospitalization and posthospital care. Perioperative stroke following coronary artery bypass grafting (CABG) is of increasing concern because as the average age of coronary bypass patients rises, so does the risk of stroke. This chapter investigates the relationship of carotid artery disease to neurologic complications following myocardial revascularization and evaluates treatment options for dealing with severe concomitant carotid and coronary artery disease (CAD).
Incidence of Perioperative Stroke
The risk of stroke coincident with CABG is well defined. In 1986, Gardner and colleagues1 found the risk of stroke to be a direct function of patient age. Patients younger than 45 years of age had a stroke rate of 0.2%, which rose to 3.0% for patients in their 60s and to 8.0% for patients older than age 75. Other risk factors associated with stroke were preexisting cerebrovascular disease, ascending aortic atherosclerosis, long cardiopulmonary bypass time, and perioperative hypotension.
Tuman and colleagues2 in 1992 investigated the effect of age on cardiac performance and neurologic injury in coronary bypass patients. Whereas the rates of low cardiac output and myocardial infarction (MI) were constant as patient age increased, the incidence of neurologic damage rose exponentially after age 65. The stroke rate rose from 0.9% for patients younger than 65 years to 8.9% for patients older than age 75.
To place the problem of the increasing patient age into a more contemporary context, at our institution the mean age of coronary artery bypass (CABG) patients rose from 56 years in 1980 to older than 67 years in 2007. In 1980 only 6% of patients were age 70 or older, whereas by 2007 more than 41% were age 70 or older, and 10% were age 80 or older.
In 2000, John and colleagues3 reported a stroke rate of 1.4% for 19,224 coronary bypass patients from the New York State Cardiac Surgical Database. Multivariable predictors of stroke included aortic calcification, renal failure, prior stroke, smoking, carotid artery disease, age, peripheral vascular disease, and diabetes. In their review of 10,860 patients having primary myocardial revascularization, Puskas and colleagues noted that stroke occurred in 2.2%.4 Multivariable predictors of stroke were age, previous transient ischemic attack, and carotid bruits.
Cost of Perioperative Stroke
Puskas and colleagues also found that perioperative stroke was associated with significantly more in-hospital morbidity, longer length of stay, and almost twice the hospital cost.4 Patients who suffered a perioperative stroke had a 23% hospital mortality rate. Roach and colleagues5 noted a 21% mortality rate for patients suffering a perioperative stroke following coronary artery bypass grafting (CABG), with a mean hospital stay of 25 days among survivors.