Pathophysiology Pathophysiology

ST Elevation Myocardial Infarction - STEMI

Early recognition and differentiation of ischaemic chest pain is important. The Cardiac Society of Australia and New Zealand (CSANZ) & The National Heart Foundation of Australia ACS Treatment Algorithm  [#national-heart-foundation-of-australia.-2011] identifies this pathway in a stepwise process.

When someone presents with symptoms consistent with ACS they should immediately have an ECG, followed by a clinical medical assessment. All patients need to be given oral aspirin150-300mg if ACS is suspected and there are no contra-indications.

If they meet the criteria for reperfusion, then dependant on their location and access to a cardiac catheter lab, and time from onset of symptoms, they should receive fibrinolysis or percutaneous coronary intervention (PCI).

ECG Criteria for STEMI:

Persistent ST elevation in two contiguous chest lead of >2mm, OR
Two contiguous limb leads of >1mm, OR
New left bundle branch block (LBBB) pattern

Non-ST Elevation Acute Coronary Syndrome – NSTEACS

When someone presents with minor or no ECG changes a careful clinical history should be taken which includes, assessment of cardiovascular risk factors and history of current symptoms. Further assessments include, physical assessment, ECG, CXR and high sensitivity troponin, among other blood tests.

Patients will be stratified as being low, intermediate or high risk according to their troponin levels, clinical presentation and risk factor profile.

To facilitate this risk stratification assessment of troponin levels may be required at 3 hours and up to 6 hours from presentation, if initially negative.

A positive troponin test supported by clinical history in the absence of other causes for elevated troponin, is strongly suggestive of acute myocardial infarction (MI) – high risk ACS.

A negative troponin test throughout this time frame in the absence of ongoing symptoms suggests a low risk category, and these patients will be referred for coronary artery disease ‘rule-out’, through exercise stress testing.

For further information on low, intermediate and high risk NSTEACS refer to the ACS treatment algorithm pathway.

  • Cardiac Rehabilitation

All patients eligible for cardiac rehabilitation should be given the opportunity to enrol in a cardiac rehabilitation  program during or shortly after their stay in hospital. Cardiac rehabilitation aims to slow or reverse disease progression and to optimise functioning by providing physical, mental and social support and improving health behaviours.

Cardiovascular risk factor education is provided in a way that motivates patients and enables them to self-manage their lifestyle risks and identified needs for change. [#woodruffe-s-neubeck-l-clark-ra-et-al.-2015]

Effective strategies to manage patients with ACS include:

For people with ischaemic heart disease, revascularisation surgery may be recommended. See cardiac surgical procedures for common open and percutaneous revascularisation procedures.

Surgery for valvular heart disease may also be performed as either an open or minimally invasive procedure.  See cardiac surgical procedures.

Following an initial diagnosis, all attempts should be made to identify the cause of HF, as this may influence management. The table below lists some examples of potential treatment options to assist management following initial diagnosis.

Table 1: Management of heart failure causes and related conditions

Potential causes and related conditions Considerations for management
Coronary artery disease Consider revascularisation (e.g., PCI, CABG)
Valvular disease Consider valve repair/replacement
Arrhythmia (e.g., AF)

Medication management to restore and maintain sinus rhythm
Electrical cardioversion may be required episodically for those with AF who show symptomatic deterioration
AF ablation may be considered for those with medication resistant AF

Ventricular arrhythmias Implantable cardioverter defibrillator(See Implantable devices)
Diabetes Optimise glycaemic control
Hyper or hypothyroidism Optimise thyroid function
Medication induced (e.g., anthracyclines) Review and appropriately modify medication management 
Alcohol related  Encourage abstinence from alcohol
Anaemia Optimise management
Pregnancy Consider timing of delivery of baby (See Pregnancy and cardiomyopathy booklet)

 

All patients with symptoms of HF, regardless of aetiology, should be considered for enrolment into a HF disease management program. [#national-heart-foundation-of-australia-and-the-cardiac-society-of-2011]  See Models of care.

Effective strategies to support patients with HF and to prolong life include:

Other treatment options

For patients with advanced HF, additional treatment options that may be considered include ventricular assist devices or cardiac transplantation. See cardiac surgical procedures.