Acute Coronary Syndromes
16/2/11
PY Mindmaps
FANZCA Notes
OHOA page 42-43
Dr Scott Harding’s (Cardiologist) Talk on Perioperative Cardiovascular Evaluation – 2009
- coronary artery disease accounts for > 30% of death in West
CLASSIFICATION
- unstable angina: ischaemic pain that is more severe, frequent or prolonged than normal
- MI: ischaemic symptoms + raised biomarkers (NSTE-ACS and STE-ACS)
HISTORY
-
take pain history
assess severity
recent MI’s
previous thrombolysis, stent or CABG
CHF symptoms
functional ability (MET’s)
medications
Canadian Cardiovascular Angina Scale
I – ordinary physical activity doesn’t cause angina (> 4 METS)
II – slight limitation or ordinary activity (2-4 METS)
III – marked limitation of ordinary activity (1-2 METS)
IV – inability to carry out any physical activity (angina @ rest)
EXAMINTION
- standard CVS examination
- may be nothing to find
- look for CCF symptoms
RISK FACTORS
-
DM
HT
lipids
family history
male
obesity
previous MI
hormone replacement for menopause
inactivity
Jeremy Fernando (2011)
INVESTIGATIONS
CARDIAC BIOMARKERS
ADVANTAGES
DISADVANTAGES
TNT and TNI
-
- elevates in non-MI cases
- assay variability for ref range
- reperfusion alters peak
- need second test if first too early
- some TNT in skeletal muscle
- incomplete understanding of
elevation post cardiac and noncardiac surgery
- baseline higher in CRF
CK
- widely used and available
- non-specific as in brain and sk
muscle
CK-MB
- level and ratio improves specificity of CK
- less sensitive and specific than TN
Myoglobin
- theoretically rapid detection
- lacks specificity and doesn’t
elevate earlier than TN
AST
- historically used with CK and LDH
- non-specific
LDH
- late onset and offset
- LD1 and LD2 in muscle
- present in many tissues
- requires isoenzymes
CRP
- marker of inflammation
- non-specific
ESR
- additive prognostic benefit
- non-specific
Copeptin
- if levels low -> rules out MI
- not specific
Troponin H-FABP
- early marker of ischaemia
- disappointing in studies
BNP
- prognostication in AMI
- difficult to interpret in critical ill.
elevates after 8 hours
elevated for 7-10 days
cardiac specific
cut of covers 99th percentile of popn.
new assays very sensitive
negative test = low 30 day cardiac risk
stratifies short and long term risk well in AMI
detects reinfarction
AUC correlates to extent of MI
Novel Biomarkers
GP-BB
- not superior to TN
Myeloperoxidase
- not superior to TN
Pregnancy associated plasma protein A
- not superior to TN
ECG
- acute AMI changes: peaked T waves with ST elevation -> gradual loss of R wave ->
development of pathological Q wave and TWI
Anteroseptal = LAD
Anterolateral = Cx
Inferior = RCA
Posterior = Cx or PDA (off RCA)
Jeremy Fernando (2011)
Location of Injury
Affected Leads
Artery
Anterior/Septal
Inferior
Lateral
True Posterior
Anterolateral
Inferolateral
V2, V3, V4
II, III, aVF
I, aVL, V3, V6
V1 and V2
I, aVL, V2-V6
II, III, aVF, aVL, V5, V6
Right ventricular
V3R, V4R
Mid or Diagonal LAD
RCA or posterolateral Cx
Cx
Posterolateral of Cx or PDA of RCA
Proximal LAD
Proximal Cx or Large LV in left
dominant system
RCA
- criteria for AMI in LBBB:
(1)
(2)
(3)
(4)
new LBBB
concordant ST elevation of > 1mm
concordant ST depression of > 1mm in V1, V2 or V3
discordant ST elevation of > 5mm
ETT
- gives an assessment of functional capacity
- looking for; ST depression, hypotension, arrhythmias
CPX Testing
- bike or hand ergometer
- under exercise O2 consumption is a linear function of Q and thus LV function
- aerobic threshold of >11mL/min/kg is able to predict survival after major abdominal surgery
accurately
Dobutamine Stress Echo
-
those that can’t exercise
up to 40mcg/kg/min
looks @ regional wall motion as an indicator of impaired perfusion
> 4 wall motion abnormalities = high risk
Nuclear Medicine Scan – Dipyridamole thallium scintography, SESTAMIBI, SPECT
MPI, PET
- coronary vasodilator (dipyridamole) and radio isotope (thallium) which is up taken into
perfused myocardium
- impaired perfusion shows up as reversible perfusion defects caused by dipyridamole causing
a steel phenonmena
- non-perfused areas show up as permanent perfusion defects
- key findings one is looking for = reversible perfusion defects, permanent perfusion defects
and cavity dilation
- negative test is very reassuring
CT Coronary Angiogram
- quantification of the amount of Ca2+ in the coronary arteries
- massive dose of radiation
- useful when wanting to completely rule out CAD burden
Jeremy Fernando (2011)
Dobutamine stress MRI
-
elegant up and coming form of stress testing
identifies wall motion abnormalities
highly accurate
safe
Technique
Sensitivity
Specificity
ETT
Exercise Stress ECHO
Dobutamine Stress ECHO
Sestamibi MPI
SPECT MPI
PET scan
70%
80
80
80
90
90
80%
85
80
75
75
80
Coronary arteriography
- delinates who needs PCI, CABG or medical management
- anatomical nature of lesions
- can stent but has issues relevant to surgery (see AHA 2007 Guidelines)
MANAGEMENT
STEACS
Reperfusion therapy
- options: thrombolysis, PCI or CABG
- ideally PCI within 90 minutes (if not thrombolyse)
- thrombolysis contraindications: absolute – active bleeding, closed HI/facial trauma in 3
months, suspected aortic dissection, risk of ICH, relative – anticoagulation, noncompressible vascular puncture, recent major surgery, > 10 minutes of CPR, internal bleeding
within 4 weeks, active peptic ulcer, poorly controlled HT, ischaemic CVA within 3 months,
pregnancy
Anti-platelet therapy
- aspirin 300mg (reduces risk of death or MI by 50% in USAP or NSTEMI)
- clopidogrel 600mg (all those that require a stent, withhold if needs a CABG)
- glycoprotein IIb/IIIa inhibitors (post NSTEMI and PCI)
Antithrombin therapy
- PCI: UFH
- thrombolysis: UFH or LMWH
Jeremy Fernando (2011)
Nitrates
- symptomatic relief
- use in CCF
- no mortality advantage however
Beta-blockers
- IV or PO
- reduce mortality
ACE-I
- use in patients with low EF, AMI and those who are vasculopaths.
Statins
- decreases risk of ischaemic events
NSTEACS
Risk stratification
- high: repetitive or prolonged pain, elevated TNT, persistent or dynamic ECG changes,
transient ST elevation, cardiogenic shock, VT, syncope, EF < 40%, prior CABG, PCI within 6
months, DM, CRF
- intermediate: rest or prolonged pain, age > 65, known IHD, 2 or more IHD risk factors,
CRF, prior aspirin use
- low: none of the above
Management
- high: aggressive medical management and coronary angiography (including LMWH)
- intermediate: inpatient monitoring and provocation testing
- low: discharged and followed up
PERIOPERATIVE MANAGEMENT
-
early consultation with cardiology
keep cardiac medications going
avoid tachycardia, hypotension, hypoxia, hypercarbia
good analgesia
keep Hb > 90g/L
high index of suspicion for perioperative MI
12 lead ECG post op day 1, 2 and 3
TNT if high risk day 2 and 3
keep anti-platelets going
Jeremy Fernando (2011)
- if develops ST elevation -> urgent angiogram
- treat angina and CHF aggressively
COMPLICATIONS
-
cardiac failure
post-infarction ischaemia
ventricular free wall rupture: pericardiocentesis and repair
ventricular septal rupture: IABP, inotropes, surgery
acute MR: afterload reduction, IABP, inotropes, surgery ASAP
right ventricular infarction: IV fluids, inotropes, AV synchrony, IABP, reperfusion
arrhythmias: correct hypoxia, acidosis, hypovolaemia, K+, Mg2+ (controversial)
cardiogenic shock: must get revascularisation (PCI or CABG) within 24 hours
thromboembolism: mural thrombus -> anticoagulate
post-MI syndrome (Dressler’s) and pericarditis
Jeremy Fernando (2011)