Louis M. Borowicz

Predictors of stroke risk in coronary artery bypass patients

BACKGROUND Stroke occurs after coronary artery bypass grafting with an incidence ranging between 0.8% and 5.2%. To identify factors associated with stroke, we prospectively examined a study cohort and tested findings in an independent validation sample. METHODS The study cohort comprised 456 patients undergoing coronary artery bypass grafting only, and the validation sample comprised 1,298 patients. Stroke was detected postoperatively by the study team and confirmed by neurologic consultation and computed tomographic scanning. RESULTS Five factors taken together were correlated with stroke: previous stroke, presence of carotid bruit, history of hypertension, increasing age, and history of diabetes mellitus. The only significant intraoperative factor was cardiopulmonary bypass time. Probabilities were calculated, and patients were placed into low, medium, and high stroke-risk groups. In the validation sample, this model was able to rank the majority of patients with stroke into the high-risk group. CONCLUSIONS These five factors taken together can identify the risk of stroke in patients having coronary artery bypass grafting. Recognition of the high-risk group will aid studies on the mechanism and prevention of stroke by modification of surgical procedures or pharmacologic intervention.

Neurobehavioural sequelae of cardiopulmonary b ypass

The development of coronary artery bypass grafting (CABG) and its effect on angina is the product of a series of technical and scientific advances. Despite these advances, however, adverse neurobehavioural outcomes continue to occur. Stroke is the most serious complication of CABG, but studies that have identified demographic and medical risk factors available before surgery are an important advance. Short-term cognitive deficits are common after CABG, but may not be specific to this procedure. However, deficits in some cognitive areas such as visuoconstruction persist over time, and may reflect parieto-occipital watershed area injury secondary to hypoperfusion or embolic factors. Risk factors for cognitive decline may be time dependent, with short-term studies identifying factors that differ from those of long-term studies. Patients with depression before surgery are likely to have persistent depression afterwards. However, depression does not account for the cognitive decline after CABG. Since CABG is increasingly done in older patients with more comorbidity, the challenge is to identify patients at risk of adverse neurocognitive outcomes and to protect them by modification of the surgical procedure or by effective medical therapy.

Cognitive Outcome After Coronary Artery Bypass: A One-Year Prospective Study

BACKGROUND Cognitive deficits have been reported in patients after coronary artery bypass grafting, but the incidence of these deficits varies widely. We studied prospectively the incidence of cognitive change and whether the changes persisted over time. METHODS Cognitive testing was done preoperatively and 1 month and 1 year postoperatively in 127 patients undergoing coronary artery bypass grafting. Tests were grouped into eight cognitive domains. A change of 0.5 standard deviation or more at 1 month and 1 year from patients preoperative Z score was the outcome measure. RESULTS We identified four main outcomes for each cognitive domain: no decline; decline and improvement; persistent decline; and late decline. Only 12% of patients showed no decline across all domains tested; 82% to 90% of patients had no decline in visual memory, psychomotor speed, motor speed, and executive function; 21% and 26% had decline and improvement in verbal memory and language; approximately 10% had persistent decline in the domains of verbal memory, visual memory, attention, and visuoconstruction; and 24% had late decline (between 1 month and 1 year) in visuoconstruction. CONCLUSIONS This study establishes that the incidence of cognitive decline varies according to the cognitive domain studied and that some patients have persistent and late cognitive changes in specific domains after coronary artery bypass grafting.

Depression and cognitive decline after coronary artery bypass grafting

BACKGROUND Depression is commonly reported after coronary artery bypass grafting (CABG), and after cardiac surgery in general. Many earlier reports relied on non-standard assessments of depression, which may have overestimated its frequency. Cognitive decline has also been reported after CABG. We assessed the frequency of depression after CABG by a validated depression measure (Center for Epidemiological Study of Depression, CES-D), and examined the relation between depression and cognitive decline. METHODS Patients were tested before CABG and 1 month and 1 year after surgery with a series of neuropsychological tests that assessed a range of cognitive areas. Depressed mood was measured by the CES-D scale, and defined as a score above 16. FINDINGS 90 (73%) of the 124 patients were not depressed before surgery, and 34 were depressed at that time. Only 12 (13%) of patients not depressed before surgery were depressed at 1 month afterwards, whereas 18 (53%) of those who were depressed before surgery were depressed at 1 month (p < 0.001). 8 (9%) patients not depressed before surgery were depressed at 1 year; 16 (47%) of patients who were depressed before CABG were depressed at 1 year (p < 0.001). Statistical analysis showed only minimal correlation-or none at all-between depression and eight areas of cognitive outcome, or between changes in depressed status and cognitive scores. INTERPRETATION Of those patients who were depressed after CABG, the large majority were depressed before surgery. There was no correlation, moreover, between depressed mood and cognitive decline after CABG, which suggests that depression alone cannot account for cognitive decline.

Stroke after cardiac surgery: short- and long-term outcomes

BACKGROUND Stroke remains a devastating complication of cardiac surgery, but stroke prevention remains elusive. Evaluation of early and long-term clinical outcomes and brain-imaging findings may provide insight into stroke prognosis, etiology, and prevention. METHODS Five thousand nine hundred seventy-one cardiac surgery patients were prospectively studied for clinical evidence of stroke. Stroke and nonstroke patients were compared by early outcomes. Data collected for stroke patients included brain imaging results, long-term functional status, and survival. Outcome predictors were then determined. RESULTS Stroke was diagnosed in 214 (3.6%) patients. Brain imaging demonstrated acute infarction in 72%; embolic in 83%, and watershed in 24%. Survival for stroke patients was 67% at 1 year and 47% at 5 years. Independent predictors of survival were cerebral infarct type, creatinine elevation, cardiopulmonary bypass time, preoperative intensive care days, postoperative awakening time, and postoperative intensive care days. Long-term disability was moderate to severe in 69%. CONCLUSIONS Stroke after cardiac surgery has profound repercussions that are independently related to infarct type and clinical factors. These data are essential for clinical decision making and prognosis determination.

Watershed Strokes After Cardiac Surgery. Diagnosis, Etiology, and Outcome

Background and Purpose— Watershed strokes are more prevalent after cardiac surgery than in other stroke populations, but their mechanism in this setting is not understood. We investigated the role of intraoperative blood pressure in the development of watershed strokes and used MRI to evaluate diagnosis and outcomes associated with this stroke subtype. Methods— From 1998 to 2003 we studied 98 patients with clinical stroke after cardiac surgery who underwent MRI with diffusion-weighted imaging. We used logistic regression to explore the relationship between mean arterial pressure and watershed infarcts, between watershed infarcts and outcome, and &khgr;2 analyses to compare detection by MRI versus CT of watershed infarcts. Results— Bilateral watershed infarcts were present on 48% of MRIs and 22% of CTs (P<0.0001). Perioperative stroke patients with bilateral watershed infarcts, compared with those with other infarct patterns, were 17.3 times more likely to die, 12.5 and 6.2 times more likely to be discharged to a skilled nursing facility and to acute rehabilitation, respectively, than to be discharged home (P=0.0004). Patients with a decrease in mean arterial pressure of at least 10 mm Hg (intraoperative compared with preoperative) were 4.1 times more likely to have bilateral watershed infarcts than other infarct patterns. Conclusions— Bilateral watershed infarcts after cardiac surgery are most reliably detected by diffusion-weighted imaging MRI and are associated with poor short-term outcome, compared with other infarct types. The mechanism may include an intraoperative drop in blood pressure from a patients baseline. These findings have implications for future clinical practice and research.

Neuropsychologic Change After Cardiac Surgery: A Critical Review

Studies that have examined neuropsychologic change after cardiac surgery address three main issues: (1) the incidence of cognitive change; (2) the identification of factors that put patients at higher risk; and (3) the evaluation of interventions to prevent these complications. This review attempts to bring together concerns associated with various study designs and to integrate the conclusions from these studies. Thirty-five studies have been examined in this review. Some of the difficulties encountered when quantifying the degree of cognitive change are related to study design, patient sampling, and deficit definition. Additionally, changing patient populations have influenced results reported from different health care settings. Increasing age and longer cardiopulmonary bypass times have been correlated with cognitive decline in a number of studies. Filtration devices and blood gas management techniques have decreased but not eliminated the number of patients who have cognitive decline. Cognitive change exists following cardiac procedures. Identification of a subgroup of patients at high risk for cognitive change has been difficult, possibly due to issues of study design. Design of future studies, which may include intraoperative or pharmacologic interventions, is dependent on identification of this high-risk group.

Is there cognitive decline 1 year after CABG?: Comparison with surgical and nonsurgical controls

Background: It is widely assumed that decline in cognition after coronary artery bypass grafting (CABG) is related to use of the cardiopulmonary bypass pump. Because most studies have not included comparable control groups, it remains unclear whether postoperative cognitive changes are specific to cardiopulmonary bypass, general aspects of surgery, or vascular pathologies of the aging brain. Methods: This nonrandomized study included four groups: CABG patients (n = 140); off-pump coronary surgery (n = 72); nonsurgical cardiac controls (NSCC) with diagnosed coronary artery disease but no surgery (n = 99); and heart healthy controls (HHC) with no cardiac risk factors (n = 69). Subjects were evaluated at baseline (preoperatively), 3 months, and 12 months. Eight cognitive domains and a global cognitive score, as well as depressive and subjective symptoms were analyzed. Results: At baseline, patients with coronary artery disease (CABG, off-pump, and NSCC) had lower performance than the HHC group in several cognitive domains. By 3 months, all groups had improved. From 3 to 12 months, there were minimal intrasubject changes for all groups. No consistent differences between the CABG and off-pump patients were observed. Conclusions: Compared with heart healthy controls (HHC), the groups with coronary artery disease had lower cognitive test scores at baseline. There was no evidence that the cognitive test performance of coronary artery bypass grafting (CABG) patients differed from that of control groups with coronary artery disease over a 1-year period. This study emphasizes the need for appropriate control groups for interpreting longitudinal changes in cognitive performance after CABG.

Impact of single clamp versus double clamp technique on neurologic outcome

BACKGROUND Atherosclerotic disease of the aorta has been identified as a risk factor for neurologic complications following coronary artery bypass grafting (CABG) due to the use of aortic clamping and manipulation. We reviewed a change from double clamp to single clamp technique to determine its impact on neurologic outcomes. METHODS Patients undergoing isolated CABG by a single surgeon were identified as having double clamp technique (DCT) (aortic cross clamp + sidebiting clamp) or single clamp technique (SCT) (aortic cross clamp only). Data were collected by study personnel and clinicians to determine stroke and neurologic injury (confusion, delirium, seizure, altered mental status, and agitation) outcomes for 461 patients. RESULTS Two hundred seventy-two patients had DCT and 189 patients had SCT performed. There were no differences in mean age, previous stroke, hypertension, or diabetes. Intraoperatively, patients with SCT had shorter bypass times (115 minutes vs 128 minutes, p = 0.001), longer aortic cross clamp time (89 minutes vs 80 minutes, p = 0.001), fewer coronary grafts (2.8 vs 3.1, p = 0.001), and had higher mean arterial blood pressure on cardiopulmonary bypass (76 mm Hg vs 69 mm Hg, p = 0.001). Postoperatively, the SCT group had fewer strokes (1.1% vs 2.9%, NS), and neurologic injuries (3.2% vs 9.6%, p = 0.008). By multivariate analysis, the factors that were related to neurologic injury were DCT (p = 0.04), age (p = 0.001), and number of coronary grafts (p = 0.03). CONCLUSIONS This experience suggests that the use of the SCT may be important in reducing neurologic injury following CABG.

Self-reported memory symptoms with coronary artery disease: a prospective study of CABG patients and nonsurgical controls.

ObjectiveSubjective memory complaints are common after coronary artery bypass grafting (CABG), but previous studies have concluded that such symptoms are more closely associated with depressed mood than objective cognitive dysfunction. We compared the incidence of self-reported memory symptoms at 3 and 12 months after CABG with that of a control group of patients with comparable risk factors for coronary artery disease but without surgery. MethodsPatients undergoing CABG (n = 140) and a demographically similar nonsurgical control group with coronary artery disease (n = 92) were followed prospectively at 3 and 12 months. At each follow-up time, participants were asked about changes since the previous evaluation in areas of memory, calculations, reading, and personality. A Functional Status Questionnaire (FSQ) and self-report measure of symptoms of depression (CES-D) were also completed. ResultsThe frequency of self-reported changes in memory, personality, and reading at 3 months was significantly higher among CABG patients than among nonsurgical controls. By contrast, there were no differences in the frequency of self-reported symptoms relating to calculations or overall rating of functional status. After adjustment for a measure of depression (CES-D rating score), the risk for self-reported memory changes remained nearly 5 times higher among the CABG patients than among control subjects. The relative risk of developing new self-reported memory symptoms between 3 and 12 months was 2.5 times higher among CABG patients than among nonsurgical controls (CI 1.24–5.02), and the overall prevalence of memory symptoms at 12 months was also higher among CABG patients (39%) than controls (14%). ConclusionsThe frequency of self-reported memory symptoms 3 and 12 months after baseline is significantly higher among CABG patients than control patients with comparable risk factors for coronary and cerebrovascular disease. These differences could not be accounted for by symptoms of depression. The self-reported cognitive symptoms appear to be relatively specific for memory and may reflect aspects of memory functioning that are not captured by traditional measures of new verbal learning and memory. The etiology of these self-reported memory symptoms remains unclear, but our findings, as well as those of others, may implicate factors other than cardiopulmonary bypass itself.