Cardiac patient peri-operative period Flashcards
What is the purpose of preoperative evaluation in cardiac patients?
- ensure adherence to guideline directed medical therapy (GDMT)
- provide clinical risk profile for informed decision making
- cardiac complications are a leading cause of morbid/mortality (17%)
What is the definition of myocardial infarction?
- Rise and or fall in serum troponin plus:
- Evidence of ischaemia based on
- ECG - new changes (path q waves)
- imaging evidence of new loss of myocardium/regional wall abnormality
- angiographic criteria (coronary thrombus on angio/autopsy)
What is MINS? Why is it significant?
Myocardial injury after non-cardiac surgery
- only relevant 30 days post
- VISION 2012 - vascular events in non cardiac surgery - showed peak trop t (TnT) associated with 30 day mortality. Used 4th gen (not high sensitivity trop) with measures in 3 post op days
- VISION 2017 used fifth gen trop - a change in 5ng/L was associated with mortality - severity of MINS (hs-TNT rise) correlated with 30 day postop mortality
updated criteria
- elevated postop hs-TNT
- resulting from myocardial ischaemia (no evidence of non-ischaemic aetiology)
- e.g. sepsis
93% with MINS have no ischaemic sxs
What is the severity scale for MINS? what are some stats surrounding how common it is?
MINS 12-18% of patients over 45 years and
patients undergoing vascular surgery with risk factors are 17% of MI
30 day mortality <20ng/L = 0.5% 20-64ng/L = 3% 65-999ng/L = 9.1% >1000ng/L = 29.6%
What is the risk of perioperative stroke?
risk = 0.08-2.9% after general surgery - covert stroke is higher.
Overt stroke has poor prognosis (death in 16-18%)
NeuroVISION - age 65 or older 7% risk of covert stroke.
- cerebral emboli on MRI in 13%
- 1/4 of patients had prior chronic infarct on postop MRI
What are the classifications of MI?
Type 1 MI
- due to plaque rupture and subsequent intraluminal thrombus
- ST elevation
Type 2 MI
- due to supply/demand mismatch
- coronary flow does not meet demand (periop stress)
- ECG changes minor
Most periop MIs are ‘silent’/aymptomatic (65-68%)
What are some risk factors for a type 2 MI?
Anything causing supply/demand mismatch: Poor supply - tachycardia - arrhythmias - CAD - hypertrophic cardiomyopathy - aortic stenosis Increased demand - sympathetic stimulation - shivering
What are some factors that may contribute to periop trop rise?
postoperative troponin rises may be
1) myocardial ischaemia
- type 1 (MI - plaque rupture/thrombus)
- type 2 (increased demand)
2) non-ischaemic cardiac causes
- cardiac failure
- cardiac trauma (pacing)
- stress cardiomyopathy
- myocarditis
3) non cardiac disease
- PE
- sepsis
- neurologic (stroke)
4) Drug induced
- chemotherapy (antracyclines - adramycin/doxorubicin, bevacizumab)
5) chronic pre-existing troponin elevation
- cardiac failure
- CKD
What are some challenges in cardiac risk stratification for non-cardiac surgery?
Multiple guidelines - ACC (US), ESC (European), CCS (Canadian)
what strategy?
- disability, death, mortality
What is the RCRI used in the Canadian risk stratification system?
RCRI gives equal weight to
- high risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular)
- IHD
- CCF
- cerebrovascular disease
- insulin dependent diabetes
- renal impairment
they combine this with proBNP to stratify necessity for the procedure and risk.
What is MACE? What are some considerations in perioperative cardiac care?
MACE - major adverse cardiac event
surgical risk
- low
- intermediate
- high risk
patient specific risk
- 3 major risk indexes
What is the NSQIP MICA risk index used by Americans?
MICA may underestimate risk because biomarker surveillance not performed
- but outperformed RCRI in vasc surgery
NSQIP
- 21 patient specific variables
- neither has external validation
Should we use cardiac biomarkers when assessing cardiac risk?
Natriuretic peptides
- BNP (brain natriuretic peptide) >92
- N-terminal pro BNP (NT-proBNP) >300
produced by myocytes in response to wall stress and ischaemia
- CCS recommends measurement if baseline risk >5%
Troponin
- Cardiac troponins (T and I) are preferred for diagnosis
What are some other risk prediction tools for cardiac risk?
P -POSSUM - only post-op, in research, over-predicts in young and under- predicts in elderly
RCRI
MACE - (MI, APO, VF, cardiac arrest, CHB)
- under-predicted in vascular patients
NSQIP
- surg risk calculator
- data about co-morbidities and operation
- nice presentation and for shared care, nil external validation
AHA prior testing pre-op
- risk via RCRI + combining it with assessment of functional capacity
European guideline
- <4 METS
- ECHO or stress depending on risk factors
How can you assess exercise tolerance/pre-op risk? what are some tools?
MET (metabolic equivalent)
- O2 sitting at rest in 40y.o. male 14mlO2/kg/min
- one flight of stairs (2 flights or 4 mets)
less than VO2 max 15 of 4 METS = high risk
1) physician and self assessment are poor predictors
2) DASI - questionaire structured
0-58 and use a formula for approximation
- only moderate
3) Troponin/BNP pre-op
- associated with increased rate of Cx
- variable thresholds used
