REM: Acute Coronary Syndrome

Acute Coronary Syndromes have a significant impact on Australian's morbidity and mortality.
Rural Australians have increased rates per capita of cardiovascular disease and poor outcomes post-Myocardial Infarction compared to their Metropolitan counterparts.

Early recognition followed by access to appropriate reperfusion strategies, plays a key role in improving the outcomes for these patients.

This is part of the Rural Emergency Module series (designed in particular for ACRRM Trainees).

Initial Assessment and Management

Consider the diagnosis: Women, the elderly, or Aboriginal/Torres Strait Islander, and patients with diabetes may have atypical presentations.

STEMI: ST segment elevations of 1 mm (0.1 mV) in 2 anatomically contiguous leads or 2 mm (0.2 mV) in 2 contiguous precordial leads, OR new left bundle branch block and presentation consistent with ACS. If ECG suspicious but not diagnostic, consult cardiology early.
Non-STEMI or unstable angina: ST segment depressions or deep T wave inversions without Q waves or possibly no ECG changes

Recognition

Recognise, send for help, gather resources and appropriate equipment.
Move to resuscitation bay
Monitoring – telemetry, SpO2
Early risk-stratification
Rapid ECG and assessment
Contact Cardiologist and retrievals if applicable early.

Airway:

Check airway

Breathing:

If breathing is inadequate, assist with BVM + high flow oxygen
Avoid routine use of oxygen therapy among patients with SaO2 > 93 %
COPD patients target SaO2 88-92%, and use oxygen in shocked patients

Circulation:

Assess Pulse, BP (measure both arms -> DDx Aortic Dissection), Cap refill.
Insert PIVC x2
Continuous cardiac monitoring
Give Aspirin 300mg
Control Blood Pressure; GTN infusion for HTN. B-Blocker (e.g. Metoprolol)
Assess for and treat left heart failure if present.

Disability:

Determine baseline neurologic function (particularly if fibrinolytic therapy is to be given)
Altered mental state => evidence of cardiogenic shock

Exposure:

Maintain Normothermia.
Check bedside Glucose

Analgesia + Antiemetics

Opioid analgesia is preferred to nitrates for the initial control of pain in the setting of STEMI.
IV morphine boluses titrated to clinical effect.
If morphine is contraindicated, consider fentanyl at 25 to 50 micrograms IV as initial equivalent dose.

Early Interventions to consider

M orphine / Fentanyl
O xygen
N itrates
A spirin
R eperfusion (thrombolysis or PCI)
C lopidegrol / Ticagrelor
H eparin

History

Signs/symptoms

Use SOCRATES/PQRRST or preferred assessment of Pain
Associated symptoms: nausea/vomiting, sweating, shortness of breath, palpitations, lethargy/fatigue

Allergies
Meds

Anticoagulants, antiplatelets, anti-hyperglycaemics
Phosphodiesterase 5 inhibitors e.g. Sildenafil (GTN may have an excessive effect if used)

PMHx:

Ischaemic Heart Disease, HTN, Diabetes, Smoker, Dyslipidaemia, LV Hypertrophy
Renal Function or known impairment
Aboriginal & Torres Strait Islander
Family Hx
Obesity

Last oral intake
Events

Syncope, collapse, cardiac arrest

Investigations

FBC, Cardiac Enzymes (Troponin), U&Es, Glu, Coags
Serial ECGs (see Quick Guide to ECG)
CXR (signs of LV Dysfunction & differential diagnoses)
Echocardiography (not routine) / A quick Bedside may provide some further clarification on level of cardiogenic shock, if present

Management

Risk Stratification:

Risk stratification will guide urgency for transfer in the context of the patient pre-existing function and location. Note risk stratification here is referring to stratifying severity of suspected/diagnosed ACS, rather than risk stratifying chest pain.

Queensland Health uses the following general recommendations around timeframes to Angiography.

Antiplatelet Therapy

Aspirin 300mg load, 100 – 150 mg daily thereafter.
P2Y12 inhibitors

Careful assessment of bleeding risk should be undertaken before using these agents.
Avoid if emergency coronary artery bypass grafting may be required, (e.g. ongoing ischaemia, extensive ECG changes, hemodynamic instability).
Ticagrelor 180 mg loading dose -> 90mg bd. For moderate to high risk NSTEACS treated conservatively or invasively, and STEMI planned for primary PCI. Avoid if emergency coronary artery bypass grafting is likely. Greater proportional benefit in renal impairment (CrCl < 60mL/min)
Clopidogrel 300mg loading dose if thrombolysis planned, 600mg if PCI planned and patient < 75yrs. 75mg daily after loading.
Prasugrel 60mg - may be used in place of clopidogrel in patients with STEMI of less than 12 hours where PCI is planned, or NTEACS after angiography and before PCI.

Anticoagulants

Consider availability and appropriateness of agent. Do not switch between agents due increased risk of bleeding.

Heparin

With PCI: Heparin (i.e. “unfractionated”) bolus dose of 5000 units should be given in cases of patients who are to receive PCI for their STEMI.
With fibrin-specific fibrinolysis: Heparin bolus loading dose with the first fibrinolytic dose and then commence heparin infusion

Enoxaparin, 1 mg/kg SC (or a reduced dose, 0.75 mg/kg SC in the elderly or those with renal impairment) 12 hourly

Glycoprotein IIb/IIIa inhibitors

Not routinely available in rural hospitals. If available should only be used in consultation with Cardiologist.

Reperfusion

Indications

All patients who present within 12 hours of symptom onset of STEMI should be considered for a reperfusion strategy, unless they have severe co-morbidities.

Choice
Reperfusion strategy depends upon;

Duration of symptoms and time to first medical contact
Locally available resources and geography
Time to commence reperfusion strategy
Location of MI
Patient related factors

Age
Comorbidities & Risk status
Contraindications to Fibrinolytics

Fibrinolysis/Thrombolysis

Typically, the only reasonable option available in rural hospitals/medical practices/prehospital. Fibrinolysis typically does not lead to improve outcomes if administered beyond 12hrs, however could be administered in consultation with a Cardiologist.

Agents

There are 3 fibrin-specific fibrinolytic agents available in Australia:

tPA (Trade name Alteplase) – Infusion
Tenecteplase (Trade name Metalyse) – Single bolus dose
Reteplase (Trade name Rapilysin) -Two standard bolus doses 30 minutes apart
Streptokinase is no longer used.

Tenecteplase + Enoxaparin is the lysis of combination of choice. Equivalent if not slightly more effective, similar cost and easiest to use.

Taken from Queensland Health Thrombolysis for STEMI Clinical Pathway (2016). Please review local protocols.

Adjunctive Treatment / Supportive Cares

Initiate adjunctive and supportive treatments unless contraindications present.

B-Blockers

In a large selection of patients, B-Blockers reduce short-term complications and improve long-term survival.
Recommended orally for both STEMI, and non-STEMI, particularly for hypertension or persistent tachycardia in absence of contraindications, irrespective of other treatment.
If significantly hypertensive, may initiate beta blocker IV instead.
Drug examples; Metoprolol 25 mg orally, Bisoprolol 5-10 mg

ACEi / ARBs

Postulated to reduce myocardial infarct expansion, ventricular remodeling, and ventricular dilatation
Shown to reduce the risk of death, reinfarction, and hospitalization for congestive heart failure (CHF) post‐acute myocardial infarction
Drug Examples; Catopril, Enalapril, Lisinopril, Rampril
ARBs (e.g. Valsartan) are believed to be a noninferior alternative in ACEI‐intolerant patients.
In Heart Failure with reduced Ejection Fraction (HFrEF) there are newer combination agents (Sacubitril/Valsartan ) which may provide additional benefit, but should ideally be started by a Cardiologist or other appropriate specialist.

Statins

Initiate cholesterol lowering therapy post-MI, unless contraindicated or there is a history of intolerance.
E.g. 80 mg of atorvastatin (best-evidence)

Supportive – FAST HUGS IN BED Please

Fluid therapy and feeding: Mg >1 , K+ >4
Analgesia, antiemetics: Opioids, Nitrates, Paracetamol. Avoid NSAIDS
Sedation; not routinely indicated
Thromboprophylaxis / Anticoagulation; see above
Head up position (30 degrees) if intubated
Ulcer prophylaxis: Recommended for patients taking DAPT, high-bleeding risk and previous GIT Bleeds. Not required for all patients.
Glucose control: Maintain Normoglycaemia.
Skin/eye care and suctioning
Indwelling catheter; not routinely indicated
Nasogastric tube; not routinely indicated
Bowel cares
Environment: Maintain Normothermia, remain in monitored environment, transfer to nearest CCU/ICU as applicable.
De-escalation (e.g. end of life issues, treatments no longer needed)
Psychosocial support (for patient, family and staff)

Life-threatening complications of Acute MI:

F ailure (heart failure)
E ffusion and tamponade

Therapy: pericardiocentesis

A rrhythmia (AV block, VT)

Therapy: correct hypoxia, acidosis, hypovolaemia, K+ >4, Mg2+ >1

R upture

Therapy: pericardiocentesis and repair

A neurysm (ventricular)
MI (Re-infarction)

Complications of therapy, e.g. haemorrhage, coronary artery dissection, stent thrombosis, surgical complications.

Overall treatment in Post-MI patients: ABCDE

A ntiplatelets (Aspirin), ACE inhibitors, Antianginals
B -blocker and Blood pressure control
C holesterol lowering / Cigarette stopping / Cardiac Rehab
D iet and Diabetes control
E ducation and Exercise

Author Description

Rural Emergency Medicine