Temporal Onset, Risk Factors, and Outcomes Associated With Stroke After Coronary Artery Bypass Grafting

Study Questions:

What are the temporal trends, risk factors, and longitudinal outcomes for stroke after coronary artery bypass grafting (CABG)?

Methods:

This was a prospective study conducted from 1982 through 2009 at a single US academic medical center among 45,432 consecutive patients (mean age, 63 [SD, 10] years) undergoing isolated primary or reoperative CABG. Strokes occurring following CABG were recorded prospectively and classified as having occurred intraoperatively or postoperatively. Complications and survival after stroke were assessed in propensity-matched groups. CABG was performed using four different operative strategies (off-pump, on-pump with beating heart, on-pump with arrested heart, and on-pump with hypothermic circulatory arrest). The main outcome measures were hospital complications and late survival.

Results:

Among 45,432 patients undergoing CABG, 705 (1.6%; 95% confidence interval [CI], 1.4%-1.7%]) experienced a stroke. The prevalence of stroke peaked in 1988 at 2.6% (95% CI, 1.9%-3.4%), then declined at 4.69% (95% CI, 4.68%-4.70%) per year (p = 0.04), despite increasing patient comorbidity. Overall, 279 strokes (40%) occurred intraoperatively and 409 (58%) occurred postoperatively (timing indeterminate in 17 patients). Postoperative stroke peaked at 40 hours, decreasing to 0.055%/day (95% CI, 0.047%-0.065%) by day 6. Risk factors for both intraoperative and postoperative stroke included older age (odds ratio, 8.5; 95% CI, 3.2-22) and variables representing arteriosclerotic burden. Intraoperative stroke rates were lowest in off-pump CABG (0.14%; 95% CI, 0.029%-0.40%) and on-pump beating-heart CABG (0%; 95% CI, 0%-1.6%), intermediate with on-pump arrested-heart CABG (0.50%; 95% CI, 0.41%-0.61%), and highest with on-pump CABG with hypothermic circulatory arrest (5.3%; 95% CI, 2.0%-11%). Patients with stroke had worse adjusted hospital outcomes, longer intensive care and postoperative stays, and worse downstream survival (mean, 11 [SD, 8.6] years).

Conclusions:

The authors concluded that among patients undergoing CABG at a single center over the past 30 years, the occurrence of stroke declined.

Perspective:

This study demonstrated that during the past 30 years, the occurrence of stroke declined despite increasing patient risk profiles, and strokes more commonly occurred postoperatively than intraoperatively. Clinical presentation and surgical technique appear to be specific to intraoperative stroke, and age and arteriosclerotic burden seem to be associated with both intraoperative and postoperative stroke. Further studies are needed to develop better strategies to identify at-risk individuals and minimize the occurrence of stroke among patients undergoing CABG.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention

Keywords: Prevalence, Outcome Assessment (Health Care), Risk, Stroke, Intensive Care, Coronary Artery Bypass, Off-Pump, Risk Factors, Coronary Artery Bypass


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