Determination of etiologic mechanisms of strokes secondary to coronary artery bypass graft surgery.

BACKGROUND AND PURPOSE: Current research focused on stroke in the setting of coronary artery bypass graft (CABG) surgery has missed important opportunities for additional understanding by failing to consider the range of different stroke mechanisms. We developed and implemented a classification system to identify the distribution and timing of stroke subtypes. METHODS: We conducted a regional study of 388 patients with the diagnosis of stroke after isolated CABG surgery in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Stroke etiology was classified into 1 of the following: hemorrhage, thromboembolic (embolic, thrombotic, lacunar), hypoperfusion, other (subtype not listed above), multiple (>or=2 competing mechanisms), or unclassified (unknown mechanism). The reliability of the classification system was determined by percent agreement and kappa statistics. RESULTS: Embolic strokes accounted for 62.1% of strokes, followed by multiple etiologies (10.1%), hypoperfusion (8.8%), lacunar (3.1%), thrombotic (1.0%), and hemorrhage (1.0%). There were 54 strokes with unknown etiology (13.9%). There were no strokes classified as "other." Nearly 45% (105/235) of the embolic and 56% (18/32) of hypoperfusion strokes occurred within the first postoperative day. CONCLUSIONS: We used a locally developed classification system to determine the etiologic mechanism of 388 strokes secondary to CABG surgery. The principal etiologic mechanism was embolic, followed by stroke having multiple mechanisms and hypoperfusion. Regardless of mechanism, strokes predominantly occurred within the first postoperative day.

Intraoperative and postoperative variables associated with strokes following cardiac surgery.

BACKGROUND: Strokes are a devastating complication of coronary artery bypass grafting (CABG) surgery. Previous work from 1992 to 2000 determined the principal mechanism of strokes occurring secondary to CABG. In the present study, we quantified the association between intraoperative and postoperative variables and stroke mechanisms while adjusting for patient and disease characteristics. METHODS: We conducted a prospective study of 13,897 patients who underwent isolated CABG in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Strokes were classified as embolic, hypoperfusion, and mixed (hemorrhage, lacunar, thrombotic, other, multiple, and unclassified). We quantified the association between the intraoperative and postoperative treatment and course variables and the stroke mechanism while adjusting for patient and disease characteristics. Patients without strokes served as the reference group for the determination of odds ratios (OR). RESULTS: Variables associated with embolic strokes included cardiopulmonary bypass time greater than 2 hours versus less than 1 hour (OR, 1.5; ptrend.03) and postoperative atrial fibrillation (OR, 2.4; P <.001). The risk of hypoperfusion strokes was increased with the duration of cardiopulmonary bypass (OR, 6.4; ptrend.01) and postoperative atrial fibrillation (OR, 5.4; P <.001). Postoperative atrial fibrillation was associated with the risk of mixed strokes (OR, 1.7; P =.04). CONCLUSIONS: After we adjusted for preoperative factors, postoperative atrial fibrillation and increasing duration of cardiopulmonary bypass remained significant predictors of embolic and hypoperfusion strokes, although to differing degrees. Prevention and management of atrial fibrillation and avoidance of prolonged exposure to extracorporeal circulation may offer leverage areas for the improvement of stroke outcomes.

Improvement of outcomes after coronary artery bypass II: a randomized trial comparing intraoperative high versus customized mean arterial pressure.

BACKGROUND AND AIM OF THE STUDY: The objective of this randomized trial was to compare the efficacy of two strategies of hemodynamic management during cardiopulmonary bypass (CPB) on morbidity, mortality, cognitive complications and deterioration in functional status. METHODS: Patients scheduled to undergo primary elective CABG were eligible. In one group, mean arterial pressure target during CPB was 80 mmHg ("high" MAP group); in the other group, MAP target was determined by patients' pre-bypass MAP ("custom" MAP group). The principal outcomes were mortality, major neurologic or cardiac complications, cognitive complications or deterioration in functional status. RESULTS: Of 412 enrolled patients, 36% were women, with overall mean age of 64.7 +/- 12.3 years. Duration of bypass was identical for the two randomization groups. Overall complication rates were similar: 16.5% of the high group and 14.6% of the custom group experienced one or more neurologic, cardiac or cognitive complications. When only cardiac and neurologic morbidity and mortality were considered, the rates were 11.7% and 12.6%, in the high and custom groups, respectively. The aggregate outcome rate, including functional deterioration, was 31.6% in the high group and 29.6% in the custom group. CONCLUSIONS: There were no statistically significant differences between the high MAP group and the custom MAP group for the combined outcome of mortality cardiac, neurologic or cognitive complications, and deterioration in the quality of life.

The association between heart rate and in-hospital mortality after coronary artery bypass graft surgery.

UNLABELLED: Avoidance of tachycardia is a commonly described goal for anesthetic management during coronary artery bypass graft (CABG) surgery. However, an association between increased intraoperative heart rate and mortality has not been described. We conducted an observational study to evaluate the association between preinduction heart rate (heart rate upon arrival to the operating room) and in-hospital mortality during CABG surgery. Data were collected on 5934 CABG patients. Fifteen percent of patients had an increased preinduction heart rate > or =80 bpm. Crude mortality was significantly more frequent among patients with increased preinduction heart rate (P(trend) = 0.002). After adjustment for baseline differences among patients, preinduction heart rate > or =80 bpm remained associated with increased mortality (P(trend) < 0.001). The increased heart rate may be a cause of the observed mortality. Alternatively, faster heart rate may be either a marker of patients with irreversible myocardial damage, or a marker of patients with limited cardiac reserve at risk for further injury. Lastly, faster heart rate may be a marker for under-use of beta-adrenergic blockade. Because the use of preoperative beta-adrenergic blockade in CABG patients is associated with improved in-hospital survival, further investigation concerning the effect of intraoperative treatment of increased heart rate with beta-adrenergic blockers on mortality after CABG surgery is warranted. IMPLICATIONS: We conducted an observational study to evaluate the association between heart rate upon arrival to the operating room (preinduction heart rate) and in-hospital mortality during coronary artery bypass graft surgery. After adjustment for baseline differences among patients, preinduction heart rate > or =80 bpm was associated with an increased in-hospital mortality after coronary artery bypass graft surgery.