The Heart Surgery Forum, Volume 7, Issue 4

Intraoperative and Postoperative Variables Associated with Strokes following Cardiac Surgery

Donald S. Likosky, PhD,¹ Louis R. Caplan, MD,² Ronald M. Weintraub, MD,³ Gregg S. Hartman, MD,¹ David J. Malenka, MD,¹ Cathy S. Ross, MS,¹ Eric S. Landis, MD,⁴ Brett Applebaum, MD,⁵ Steven P. Braff, MD,6 Gerald T. O'Connor, PhD,¹

for the Northern New England Cardiovascular Disease Study Group, Lebanon, New Hampshire ¹Departments of Medicine and Community and Family Medicine, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire; Departments of ²Neurology and ³Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts; ⁴Department of Radiology, Catholic Medical Center, Manchester, New Hampshire; ⁵Department of Radiology, Maine Medical Center, Portland, Maine; 6Department of Radiology, Fletcher Allen Health Care, Burlington, Vermont, USA

ABSTRACT

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.

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