Despite an increase in risk profiles of patients who underwent coronary artery bypass graft, the occurrence of stroke after CABG has declined, according to a study.
Cleveland Clinic researchers examined the prevalence and timing of perioperative stroke, along with associated patient and surgical factors. The study, which in the Jan. 26 edition of Journal of the American Medical Association, included data from 45,432 patients (average age 63) who underwent primary or reoperative CABG surgery from 1982 through 2009 at a U.S. academic medical center.
Strokes occurring following CABG were recorded prospectively and classified as having occurred intraoperatively or postoperatively. Data also included information on four different CABG operative strategies: off-pump, on-pump with beating heart, on-pump with arrested heart, and on-pump with hypothermic circulatory arrest.
Of the patients, 1.6% experienced a stroke. The frequency was 2.6% in 1988, then declined each year despite an increasing patient risk profile such as higher prevalence of preoperative stroke, hypertension, and diabetes.
According to the authors, possible reasons for the decrease include improved preoperative assessment, intraoperative anesthetic and surgical techniques, and postoperative care.
Among the patients who had a stroke, intraoperative stroke occurred in 40% and postoperative stroke occurred in 58%. The timing was undetermined in the remaining 2%.
Risk factors for both intraoperative and postoperative stroke include older age, previous stroke, preoperative atrial fibrillation, and on-pump CABG with hypothermic circulatory arrest. Stroke risk also increased with a rise in the number of arteriosclerotic co-existing conditions.
For intraoperative strokes, rates were highest among patients who had on-pump CABG with hypothermic circulatory arrest (5.3%) and lowest among those who had off-pump CABG (0.14%) and on-pump beating-heart CABG (0%). Risk of intraoperative stroke was intermediate for those undergoing on-pump arrested-heart CABG (0.50%).
Patients who experienced a stroke had substantially worse hospital outcomes, even after adjustment for preoperative factors: 19% mortality compared with 3.7% for patients who did not have a stroke; 44% prolonged ventilation compared with 15%; and 13% renal failure compared with 4.3%. They also experienced substantially longer ICU and postoperative lengths of stay.