myocardial infarction rupert and fergus [email protected] [email protected]
TRANSCRIPT
Myocardial InfarctionRupert and Fergus
[email protected]@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.