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Peri-operative adverse cardiac events
Identifying at risk patients and mitigating risk
Dr Simon Arnett /
Dr Steven Sutcliffe
Terminology
MACE
Major adverse cardiac event = acute coronary syndrome,
need for urgent revascularisation, malignant arrhythmia.
Type I MI
Raised troponin due to thrombotic occlusion of coronary
artery (ACS).
Type II MI
Supply / demand mismatch secondary to a stenotic vessel
with ischaemia in times of increased demand.
How to diagnose a MACE
Includes both the standard
ACS definition
Suggestive clinical history
Raised biomarkers
ECG changes
And
Raised biomarkers in the absence of ECG changes or symptoms,
in the absence of an alternative cause of elevated biomarkers.
The criteria are laxer in perioperative patients because:
Pts are sedated/under anaesthesia at the time of maximum
hemodynamic stress, therefore insensate to symptoms.
Pts are given liberal analgesia post op, again masking clinical
manifestations
65% of MACE events are missed due to the above factors.
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Incidence of MACE
In high risk surgeries occurs in 5% of all pts undergoing noncardiac surgery.
1/3 of all peri-operative deaths are due to MACE.
Majority occur within T+ 48hrs post-surgery.
Risk Factors for peri-operative MACE
General medical factors
Age >75
Male sex
CKD
Known macrovascular disease; established coronary
artery disease, peripheral vascular disease,
cerebrovascular disease
DM
Poor baseline exertional tolerance (<4 METS)
Cardiac conditions
Heart failure (particularly decompensated)
AF
Hypertension
Severe Aortic Stenosis
There are several risk stratification tools:
RCRI (AKA Lee index)
ACS-NSQIP
MICA
However, these tools were validated in nonemergent surgical scenarios, underestimate
risk in surgical emergencies.
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When should surgery be delayed prior to a cardiac assessment?
Recent ACS event
Severe angina
Decompensated heart failure
Significant arrhythmia
- AV blocks – severe type I, Mobitz type II, CHB
- Symptomatic non-sustained VT
- new SVT with rapid ventricular responses >100
- Symptomatic bradycardia
Severe (symptomatic) valvular disease – symptomatic aortic or mitral disease
Which surgeries carry the highest risk of MACE?
Highest risk (quoted risk of peri-operative MACE ~5%) is associated with vascular surgery
- Aortic repair
- Any major vascular surgery
- Peripheral vascular surgery e.g. fem-pop bypass
Higher risk also associated with open intra-thoracic and intra-abdominal surgery
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What peri-operative events are risk factors for MACE?
Recent Hx factors;
Recent acute life-threatening insults (e.g. AAA rupture)
Recent ACS event
Recent coronary artery stent (6/12)
Recent stroke (3/12)
Acute trauma
Urgent or emergency surgery
How much risk is too much risk?
Same philosophy as general approach to ACS/IHD presentations;
<1% risk of peri-operative MACE – no further testing warranted
>1% risk of perioperative MACE – pts should be investigated prior to surgical procedure
What perioperative events can exacerbate MACE?
Hypotension, Tachycardia, hypoxaemia
Significant haemorrhage
Pain +++
Mitigating risk of MACE
1. Aspirin
- Aspirin as a secondary prevention
measure can be discontinued 5-7 days
prior to surgery (this does increase risk,
and should be joint decision between
medical and surgical teams)
- Aspirin should not be commenced
prior to surgery as a primary prevention
measure - no benefit in MACE,
increased major bleeding risk (POISE-2)
2. Statins
- Those on statins should continue
- Pts at high risk of perioperative MACE
(DM, PVD, carotid artery disease, AAA,
CKD) should be commenced on high
dose statin as soon as possible
3. Beta-Blockers
- DECREASE trial (Poldermans et al) –
decreased mortality and peri-operative
MACE event rate
→ Author of same subsequently
convicted of fraud and publication has
been withdrawn
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Is there a role for Anticoagulation?
Pts previously on thromboprophylaxis
Requirement for bridging
anticoagulation depends on
thromboembolism risk.
Low risk
No requirement for bridging after
cessation of oral anticoagulation preop.
High risk
DO require bridging anticoagulation.
High risk includes stroke 3/12, mechanical valves, high risk CHADS2, VTE 3/12, previous
thromboembolism with interruption, recent coronary stent.
 If the risk elevation is transient (i.e. recent stroke, VTE) – where possible, delay surgery
until risk decreases.
 Certain procedures do not require discontinuation of anticoagulation – dental,
cutaneous, cardiac implantation, cardiac catheter ablation.
 Generally, less requirement for bridging with use of NOACs due to rapid onset/offset
compared to warfarin.
Ceasing and Recommencing Anticoagulation
Anticoagulant
Stop prior
Restart
Warfarin
Five days prior
Check INR day before, if >1.5
→ low dose vit K
12-24 hrs post surg if no
complications
Dabigatran
(thrombin)
Normal renal function – 2 days
Impaired renal function – 4 days
Within 24 hrs, but delay 2-3
days if high risk bleeding
Rivaroxaban,
apixaban (Xa)
~2 days, less for low risk, more
for high risk bleeding
Within 24 hrs, but delay 2-3
days if high risk bleeding
Learning Points
 Perioperative MACE is common, and commonly missed.
 There are well defined risk factors, and risk calculation tools
available, but be mindful of limitations.
 Be careful with post procedure hypotension, tachycardia,
hypoxaemia, significant haemorrhage, pain +++
 Statins are almost always a good idea. Aspirin is problematic
peri-procedurally.
 Beta blockers were once thought to be mainstay, now
known to be problematic.
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Suggested Reading
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Devereaux et al 2014 Aspirin in pts undergoing noncardiac surgery NEJM 370: 1494-1503
Devereaux 2015 Cardiac complications in patients undergoing major noncardiac surgery
NEJM 373: 2258-2269
Auebach 2008 Changing the practice of perioperative cardioprotection Circ Cardiovasc
Qual Outcomes 1:58-61