Myocardial InfarctionRupert and Fergus

rupert.larkin@warwick.ac.ukF.M.A.Liggins@warwick.ac.uk

What is Myocardial Infarction?

• MI is defined as..

What is Myocardial Infarction?

• MI is defined as..

‘Myocardial cell death occurring due to a prolonged mismatch between perfusion and demand, usually caused by an occlusion in the coronary arteries.’

• MI is a type of Acute Coronary Syndrome (ACS)

Acute Coronary Syndrome (ACS)

• ACS refers to acute myocardial ischaemia caused by atherosclerotic coronary disease and includes:– ST-elevation MI (STEMI) [Myocyte death]– Non ST-elevation MI (NSTEMI) [Myocyte death]– Unstable angina

• These terms are used as a framework for guiding management.

Acute Coronary Syndrome (ACS)

ACS

STEMI Unstable AnginaNSTEMI

Should be considered for immediate reperfusion therapy

NSTEMI & UA patients do not benefit from immediate reperfusion therapy (note that

reperfusion therapy may be chosen later, just not as first line treatment)

Signs and Symptoms of MI

• Symptoms;

• Signs;

Signs and Symptoms of MI

• Symptoms; Acute central chest pain (heavy/crushing, can radiate to jaw and left arm) lasting >15 mins Nausea Sweatiness Dyspnoea Palpitations

• Signs;

Signs and Symptoms of MI

• Symptoms; Acute central chest pain (heavy/crushing, can radiate to jaw and left arm) lasting >15 mins Nausea Sweatiness Dyspnoea Palpitations

• Signs; Distress Anxiety Pallor Tachycardia Raised BP Signs of heart failure – JVP, 3rd heart sounds, basal crepitation's (why crepitation's?) Pan-systolic murmur

Risk Factors

• Non-modifiable;

• Modifiable;

Risk Factors

• Non-modifiable; Age Male FHx of IHD

• Modifiable;

Risk Factors

• Non-modifiable; Age Male FHx of IHD

• Modifiable; Smoking Hypertension DM Hyperlipidaemia Obesity Sedentary lifestyle

Differential Diagnosis(think central chest pain!)

Differential Diagnosis(think central chest pain!)

• Angina• Pneumothorax• Pericarditis • Myocarditis• PE• Costrochondritis• Oesophageal reflux/spasm• Aortic dissection (usually pain between shoulder blades)

• Anxiety/panic attack

Initial Management of ACS symptoms

• What do you do initially?– Remember, you don’t know if its STEMI/NSTEMI/UA yet!

• 1st

• 2nd

• 3rd

Initial Management of ACS symptoms

• What do you do initially?– Remember, you don’t know if its STEMI/NSTEMI/UA yet!

• 1st 12-lead ECG

• 2nd IV access: FBC, Glucose, lipids, U & E, Cardiac Enzymes

• 3rd Stabilisation & symptomatic relief!

Initial Management of ACS symptoms

Stabilisation & symptomatic relief

Initial Management of ACS symptoms

Stabilisation & symptomatic relief  [MONA]•Morphine Pain relief Reduced associated sympathetic activity Decreased myocardial O2 demand

•Oxygen

•Nitrates  GTN – how does this work to relieve the pain?

•Aspirin

Key question for subsequent management is whether there is STEMI or not

ECG

• The ECG can tell you about the pattern of ischaemia/infarction e.g. STEMI, NSTEMI, UA

• Helps decide upon management

• Can diagnose arrhythmias

ECG - STEMI

• STEMI (classical presentation)

ECG - STEMI

• STEMI (classical presentation)- Minutes-hours Tall T waves, ST elevation- Usually indicates a transmural infarction (full wall thickness)

ECG - NSTEMI

• NSTEMI

ECG - NSTEMI

• NSTEMI- T wave depression- Non-specific changes- In 20% MI, ECG may be normal initially

CXR

• Why perform a CXR?

• Look for…

CXR

• Why perform a CXR?– Help rule out differentials for chest pain/dyspnoea– MI can cause heart failure and consequent pulmonary oedema – how?

• Look for…– Cardiomegaly– Pulmonary oedema– Widened mediastinum could indicate aortic rupture

• Do not delay treatment for CXR

Cardiac Enzymes

• Cardiac Troponin T and I - What is the normal role of these?– Most sensitive and specific markers for myocardial necrosis- Levels increase 3-12 hours from onset of chest pain- Peak 24-48 hours- Return to normal levels in 5-14 days

• Creatine Kinase- 3 types of CK, CK-MB is variant used in diagnosis of acute MI.- Levels begin to ↑ 3-12hrs after event, peak within 24hrs and return to normal after 48-

72 hrs.- MI sensitivity = 95% with high specificity - What are the definitions of these?

• Myoglobin - What is it? - Levels rise within 1-4 hours. - High sensitivity, low specificity

Diagnosis

Management of STEMI

• STEMI  Reperfusion therapy!

• Percutaneous Coronary Intervention (PCI) (stenting) if <90 mins since first medical contact

• Thrombolysis of PCI not available within first 90 mins of first medical contact

– Efficacy decreases with time from symptom onset – ideally initiate within 3 hours– Check for contraindications e.g. previous intracranial haemorrhage– E.g. Alteplase (Tissue Plasminogen Activator)

Management of NSTEMI

• Immediately – Beta-blocker e.g. Atenolol– P2Y12 inhibitor e.g. Clopidogrel (+ consider LMW Heparin)– Assess risk of further CV events e.g. GRACE or TIMI score

• Then• Decide whether the patient requires an invasive or non-invasive treatment approach Assess risk of further CV events

using GRACE or TIMI score  + Coronary angiogram to help decide

• Invasive revascularisation (stenting) for high risk patients such as those with – Elevated cardiac biomarkers (troponin T or I)– New or presumably new ST-segment depression– High risk score or Diabetes– PCI during previous 6 months– Prior CABG

• Non-invasive treatment  Conservative, early medical management strategy for those without above high risk features and with a low risk score.