Perioperative Infarcts:Epidemiology, predictors and

post-op monitoring

Dr Carol ChongGeriatrician

Northern Health, Epping, Victoria, Australia

Friday Nov 3rd, 2017 1pm

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• Orthopaedic Intern, 1st job

• Aged Care registrar – Orthopaedic-geriatric unit

• Incidence of asymptomatic Troponin elevations after orthopaedic surgery

• RCT intervention

• M.D 2008-2011

How I became interested in this field

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• How common are peri-op infarcts?

– Cardiac complications (MI, Heart Failure, VT) up to 5% of patients

– Mortality after MI in hospital 25-65% at 1 year

Epidemiology

Devereaux et al CMAJ 2005

Lowe et al Med J Aust 2006

Lowe et al Med J Aust 2006

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How do we define an AMI after non-cardiac surgery?

• Third Universal definition of Myocardial Infarction

– Redefined in 2007, updated in 2012

– Emphasised rise and fall of cardiac markers with level above 99th percentile of upper reference range

– Together with symptoms of ischaemia or ECG changes

Thygesen et al 2007 J Am Coll Cardiol

Thygesen et al 2012 Circulation

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• Type I: Spontaneous MI

• Type II: MI secondary to an ischaemic imbalance

• Type III: MI resulting in death when biomarker values are unavailable

• Type IVa: MI related to PCI

• Type IVb: MI related to stent thrombosis

• Type V: MI related to CABG

Universal Classification of MI

Thygesen et al 2012 Circulation

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• Type 1 peri-op MI – traditional for pts with non-surgically related MI.

– Arterial thrombosis of coronary artery by plaque fissuring or acute luminal thrombosis in areas of stenosis

– Dawood et al, landmark study – Autopsy study –fatal post-op MI 42 pts

-significant atherosclerotic obstruction in >50%

-Site of infarct not necessarily site of most severe stenosis

2 proposed mechanisms

Dawood et al Int J Cardiol 1996

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• Demand ischaemia – hemodynamic changes may relate to troponin abnormalities

• Angiography post- MI – presence of chronic severe coronary artery disease without thrombus or ulcerated plaques

• Imbalance between myocardial oxygen supply and demand

Type II peri-op MI

Modesti et al Intern Emerg Med 2006

McFalls et al Eur Hear J 2008

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Peri-operative Myocardial Infarction

• Mostly silent eg. delirium, analgesics blunt pain sensation

• Either end of surgery or 24-96 hours later

• ECG changes non-Q wave

Sun et al Am Heart J 2007

Badner et al Anesthesiology 1998

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Pathophysiology of peri-op MI

• Complex!

• Surgery sympathetic system

• Inflammation

• Hypoxia

• Increased pro inflammatory cytokines

• Platelet activation

• Hypercoagulable environment

• Oxygen demand Increases

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The Cardiac Myocyte and Troponins

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Troponin I

• Exists in 2 forms within myocardium

1. Cytosolic component 3% Troponin I

2. Structural (myofibrillar) form

• Unbound cytosolic component released acutely

– Concept of reversible ischaemia

• In practice, difficult to distinguish clincally

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Incidence of post-op troponinelevations

• Orthopaedic series

– Incidence between 5.9 - 52.9%

• Studied mainly in the vascular population

– Incidence 8-33%

Jules-Elysse et al J Clin Anesth 2001

Mouzopoulos et al J Trauma 2007

Ausset et al Arch Orthop Trauma Surg 2008

Dawson-Bowling et al Injury 2008

Chong et al Age Ageing 2009

Kim et al Circulation 2002

Landesberg et al J Am Coll Cardiol 2005

Oscarsson et al Acta Anaesthesia Scand 2004

Barbagallo et al J Clin Anesthesia 2006

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• Incidence likely related to sensitivity of biomarker

• Biomarker of myocardial injury

• Non specific marker of illness

• Determining cause of troponin elevation helps to guide management

– For pts with a high pretest probability of ACS due to a thrombotic event, diagnostic value of troponin is useful

– Difficulty lies in troponin as a screening tool if patients with a low pre-test probability are tested

Troponin Issues

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• Concept of Myocardial Infarction and Myocardial Injury after Noncardiac Surgery (MINS)

– Broader term than MI.

– Results in myocardial injury during (+/-necrosis) or within the first 30 days after non-cardiac surgery

– Prognostically relevant

– Due to an ischaemic etiology

– May not have the typical features eg. symptoms, ECG

MI and MINS

Botto et al Anaesthesiology 2014

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• VISION study (Vascular Events in Noncardiac Surgical Patient Cohort Evaluation Study)

• Trop measured 6-12 hours after surgery and days 1,2,3 post op.

• 15,065 pts

• Trop >0.03ng/ml

• 11.6% post-op troponin elevation

• 8% MINS

MINS incidence

Botto et al Anaesthesiology 2014

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• 41.8% fulfilled the universal definition of MI

• Only 15% with MINS had an ischaemic symptom

• 30 day mortality (115 pts) was 9.8% in MINS pts and 1.1% without.

• Vascular cause of death in 62 (53.9%)

• 10 fold mortality with Troponin >0.30

MINS incidence 8% (VISION)

Botto et al Anaesthesiology 2014

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• MI and MINS – worse short and long term outcomes

• In hospital mortality after peri-op MI 5-25%

Prognosis

Devereaux et alCMAJ 2005

Badner Anesthesiology 1998

Levy et al Anesthesiology 2011

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• 1977 Goldman et al created a risk evaluation system (NEJM)

• 1999 Lee et al – Revised Goldman Cardiac Risk Index

Predictors

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Revised Goldman Cardiac Risk Index

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• American College of Surgeons National Surgical Quality Improvement Program (NSQIP) Calculator

Other predictors

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• Is screening indicated to detecting cardiac injury peri-operatively?

Post-op monitoring

Post-op monitoring

• Is screening indicated to detecting cardiac injury peri-operatively?

– Perhaps for high risk surgery

– Using Troponin and ECGs

• Recommendations

• 2014 ACC/AHA guidelines – usefulness uncertain

• 2014 European Society of Cardiology – may be considered

• 3rd Universal definition of MI – before and 48-72hrs after in high risk pt’s

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1. Will the test change the care of my patient eg. Asymptomatic pt with Normal ECG and mild troponin elevation

2. What are the probability and potential adverse consequences of a false positive result eg. Anticoagulating, bleeding risk, PCI risk

3. Is the pt in danger in the short term if I do not perform the test?

Screening Issues

Beckman Circulation 2013

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Troponin I

• Incidence of a troponin elevation post-operatively was 70/187 (37.4%)randomised.

• 12 patients had a post-op AMI (6.4%)

• SC: 5 patients 41.7% dead at 6 months

• CC: 7 patients 42.8% dead at 6 months

• 1 year mortality No difference between randomised groups

• 6/35 (17.1%) dead in each group (p=1.000)

• Troponin was a prognostic marker

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• B blockers – POISE

• Aspirin and clonidine - POISE II

• Ivabradine and atorvastatin

• Dabigatran (a Direct Thrombin Inhibitor) and Omeprazole (a Proton-pump Inhibitor) in Patients Suffering Myocardial Injury after Noncardiac Surgery (ongoing Oct 2017) Devereaux

Preventative strategies

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• Fewer in bblocker group 244 (5.8%) versus placebo 290 (6.9%) reached primary endpont (composite CV death, non fatal MI and nonfatal cardiac arrest)

• MI 5% at 30 days (4.2% bblocker vs 5.7% placebo)

• More death in bblocker group 29 (3.1%) vs 97 (2.3%) Hr 1.33, 1.03-1.74, p=0.0317)

• More stroke 41 (1%) vs 19 (0.5%) HR 2.17, 1.26-3.74, p=0.0053).

• Clinically significant hypotension and stroke explains increased risk of death

POISE Trial results-8351 pts at risk of atherosclerotic disease

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• Few prospective RCTs in this field

• Newer cardiac Ix – Coronary calcium scores, Cardiac MRI

• Use of peri-op beta blockers controversial –eg. Duration of initiation prior to surgery, dose and titration

• Value of testing biomarkers peri-op needs more Ix.

Screening/Monitoring – more research needed

Summary

• Post-op AMI assoc with worse outcomes

• Troponin elevations confer a worse prognosis

• However, there are no validated treatments for asymptomatic troponin elevations post-op as yet – thus screening is not recommended