Stroke Flashcards
For how long should elective surgery be delayed after previous stroke? based on what?
9 months- of course risks of surgical delay must be balanced (eg. cancer surg)
Large Danish cohort- nearly 500,000 elective surgical pts, risk of periop ischaemic stroke, MACE & mortality is lowest around 9/12 post-stroke
PTS WHO’D HAD A STROKE <3/12 BEFORE SURGERY HAD A 68-FOLD HIGHER RISK OF RECURRENT STROKE, increased periop risk associated with prior stroke was similar between low- and high-risk surgeries
In what proportion of pts undergoing non-cardiac surgery does covert stroke occur? what trial showed this? what’s meant by covert stroke?
7% & it’s associated with postop delirium & postop cognitive decline
found in the NeuroVISION trial, a prospective cohort study of >1000 elective non-cardiac surg pts >65yo, having perfusion-weighted MRI within 1 week of surgery
in contrast to overt stroke- an acute brain infarct with clinical manifestations lasting >24hrs- covert stroke= a brain infarct not recognised @ the time of onset (subtle manifestations) but is detected on brain imaging
What’s perioperative stroke?
brain infarction of ischaemic or haemorrhagic aetiology that occurs during surgery or within 30 days after surgery
What’s the predominant aetiology of perioperative strokes?
cardioembolic
What are patient risk factors for perioperative stroke?
older age, esp >85yo Hx of prior stroke or TIA AF HTN valvular heart disease renal disease CCF DM smoker or COPD PFO (2-fold increase risk in the year after surgery but risk reduced by postop anti-thrombotic therapy- discuss w surgeon & neurology) Hx migraine, esp migraine with aura= nearly 2x increased risk of periop stroke carotid stenosis doesn't have a well defined role in perioperative stroke *sex & race no conclusive evidence
What are the highest risk surgical procedures associated with periop stroke?
vascular (CEA is 3-7%), thoracic (cardiac 1-10%) & transplant = highest risk
also endocrine, burn, otolaryngology surgery, hemicolectomy
O&G= lowest risk
For which patients is CEA or stunting generally recommended?
symptomatic high grade (50-99%) stenosis
relative risks & benefits of intervention for asymptomatic pts is less well defined
Perioperative approach to stroke prevention/detection
Pre-op:
Delay elective surgery 9/12 post stroke if possible (don’t delay urgent surgery)
Evaluate pt for risk factors, including carotid stenosis- generally carotid artery stenting or CEA isn’t recommended before surgery if asymptomatic
counsel high-risk pts
on anticoagulation? routine bridging for AF not recommended (BRIDGE trial- ACC/AHA consider risk/benefit)
periop aspirin therapy not recommended (POISE 2- no change death or non-fatal MI but increased risk major bleeding)
prophylactic Rx of asymptomatic carotid artery disease not recommended
new initiation of B blockers not recommended (POISE- higher incidence of death & stroke despite lower rate MI)
Intra-op:
no evidence re: mode of anaesthesia impacting stroke risk
avoid relative hypotension
sitting position for shoulder surgery not associated with high rate of overt stroke
Postop:
- high index of suspicion
- no validated screening tool currently exists for surgical pts (mNHISS validated in non-surgical population)
- if clinical Ax suggests stroke, immediate imaging using non-con CT or MRI (ischaemic or haemorrhagic?)
- thorough assessment incl BP, SpO2, temp, BGL, routine haematological studies, thorough neuro Ax
- urgent consult with stroke neurology service- ?BP Mx, thrombolysis or endovascular thrombectomy
What was the BRIDGE trial & what were it’s 2 main important findings? how do these findings interact with the ESC & ACC/AHA guidelines?
designed to answer the question whether bridging with LMWH was non-inferior to not bridging for prevention of arterial thromboembolism for pts on warfarin undergoing elective surgery.
not bridging was non inferior to bridging wrt prevention of arterial thromboembolism
bridging with LMWH resulted in nearly 3-fold incr incidence of major bleeding
Bottom line: bridging of warfarin should be avoided for most pts with AF
for pts at higher risk of periprocedural stroke (CHADS2 >3, recent TIA, rheumatic heart disease or mechanical heart valve), must consider relative risks of stroke & bleeding, duration not anti coagulated.
Should pts taking DOACS for AF be bridged?
no- temporary interruption for surgery= low rate (0.3%) arterial thromboembolism or ischaemic stroke
What was the POISE-2 trial & it’s main findings? clinical implications?
randomised 10,000 pts undergoing non-cardiac surgery to receive aspirin or placebo
no difference in primary outcome (death or non-fatal MI), aspirin din’t result in significant reduction in stroke
perioperative aspirin resulted in an increased risk of major bleeding
ie: perioperative continuation or initiation of aspirin doesn’t appear to confer protection against MI or stroke for non-cardiac non-neurological surgery
In the absence of stunting, current guidelines recommend against initiating & continuing aspirin for the prevention of cardiac events
What was the POISE trial & it’s main findings? clinical implications?
randomised pts to extended-release metoprolol or placebo
although metoprolol reduced the incidence of MI, it resulted in more deaths & a higher rate of stroke
MAY be due to clinically significant hypotension (more common in metoprolol group)
metoprolol is not cardio-selective so may not have been the most appropriate choice
a separate meta-analysis has found that b-blockers don’t reduce the risk of stroke in vascular surgical pts
beta-blockers don’t reduce the risk of perioperative stroke in low-risk pts & may increase risk of stroke if initiated immediately before surgery.
HOWEVER abrupt cessation of B-blockers is associated with increased risk 30-day periop mortality- so chronic B-blocker therapy should be continued.
What did a Danish cohort of pts undergoing emergency surgery after stroke find? clinical implications?
risk of periop stroke, CV events & mortality was highest in pts who had a previous stroke within 3/12 of surgery
Those who underwent urgent surgery <72hrs after stroke had LOWER risk of MACE cf those who underwent surgery 4-14 days post stroke.
This MAY be due to dysregulated cerebral autoregulation.
Urgent surgery shouldn’t be delayed in pts who’ve had a recent stroke but tight haemodynamic control is recommended given concerns about autoregulation.
When do most perioperative strokes occur?
postoperatively
peak incidence 1-2 days postop, only 10% present on day of surgery
What’s the evidence base behind tight intraop BP control?
conflicting wrt relationship between arterial pressure & periop stroke. further data to define risk more precisely & determine if interventions to improve BP reduce incidence & severity of postop stroke.
POISE 3 trial is investigating the role of hypoT in pts undergoing non-cardiac surgery at risk of perioperative CV events including stroke.
