Perioperative Stroke

review article Selim M. NEJM 2007; 356:706-713.
Tidbits and quick facts cited from the literature
1. After bypass most strokes are ischemic and embolic, not hemorrhagic

2. 45 % occur in first day, 55% in second or subsequent days

3. Delayed stroke is due to post operative atrial fibrillation, that occurs in 30-50% of patients; coagulopathy with decreased fibrinolysis and activation of the hemostatic system; dehydration; stasis, and perioperative withholding of antiplatelet agents or anticoagulants. Rare causes are air, fat or paradoxical embolus or arterial dissection due to neck manipulation in surgery.

4. Most post CABG strokes, contrary to myth, are not related to hypoperfusion

5. Risk stratification method called "bootstrapping" was developed by the Northern New England Cardiovascular Study Group. Risk factors are numerous but the model weights most highly advanced age, urgent surgery, creatinine > 2.0 and a specific history of stroke or TIA within six months, especially with a symptomatic carotid artery (see separate post)

6. Risk of stroke from asymptomatic carotid lesions is higher than those without but still low and in most cases does not warrant two procedures.

7. Preop eval for risk factors might include MRI/ MRA/TCD / pre op ECHO

8. Predictors of postop atrial fibrillation are: advanced age, perioperative CHF or low EF; perioperative withdrawal of ACE inhibitors or B blockers; prior inferior wall MI; combined CABG/valve replacement and high post op magnesium

9. The discontinuation of warfarin or aspirin leads to increased perioperative risk especially in patients with coexisting CAD. The rate was 0.6 % with discontinuation without perioperative heparin and 0.0 % with heparin. The rate of major bleeding if the patient was on anticoagulation was 0.2 % for dental procedures, 0 % for arthrocentesis, cataract surgery, and upper or lower endoscopy without biopsy. One study (Larson et al., Chest, 2005) showed that moderate dose warfarin therapy (INR around 2.0) was safe and effective during knee or hip replacement.

10. Hyperglycemia intra or postoperatively is associated with higher rates of atrial fibrillation, stroke and death.

11. Treatment of electrolyte abnormalities and infections post operatively reduces stroke

12. The use of aspirin after CEA or CABG reduces stroke without increasing bleeding complications.

13. Whereas i-v t PA is contraindicated, arterial t PA or clot disruption is feasible postoperatively. In one study, 80 % of patients (n=36) who received arterial t PA within 6 hours after a perioperative stroke had partial or complete recanalization, 38 % had minimal or no residual disability at discharge, and the mortality rate was similar to non perioperative patients undergoing the procedure. 17 % had bleeding at the operative site, but most was minor.

14. Future directions include possible use of perioperative neuroprotective drugs; statins or beta blockers, or aprotinin are mentioned as possible worthy drugs to use in the setting.