Myocardial Infarction Flashcards
Definition of ACS - acute coronary syndrome
Includes three conditions with a common pathology
- unstable angina
- STEMI
- NSTEMI
What is the common pathology in ACS?
Rupture of the fibrous cap of a coronary artery, atherosclerotic plaque. This causes a thrombus, followed by inflammation.
Rarely can also be caused by emboli, coronary artery spasm or vasculitis
What is a myocardial infarction?
Myocardial ischaemia and death, releasing troponin into the blood
Ischaemia is a lack of blood supply to an area +/- cell death
What is the difference between a myocardial infarction and unstable angina?
MIs have troponin rises, unstable angina does not
What is the difference between a STEMI and an NSTEMI?
STEMI
- ACS with ST elevation rise or a new onset LBBB
NSTEMI
- ACS with positive troponin and no ST elevation
- may show ST depression, T-wave inversion, non-specific changes or a normal ECG
Risk factors for ACS
Non-modifiable - age - gender - family history of IHD before the age of 55 Modifiable - smoking - hypertension - hyperlipidaemia - obesity - diabetes mellitus - sedentary lifestyle - cocaine use
What are the and symptoms of ACS
Acute central chest pain - lasts more than 20 mins - associated with nausea, sweating, dyspnoea and palpitations Sense of impending doom Syncope Tachycardia Vomiting and sinus bradycardia - due to excessive vagal stimulation
What are the signs of ACS
Pallor Sweating Increased pulse Decreased BP 4th heart sound added Signs of heart failure - increased JVP - 3rd heart sound - basal crepitations - pansystolic murmur - pericardial friction rub
What are the signs and symptoms of a silent MI
No chest pain Syncope Pulmonary oedema Epigastric pain Vomiting Post-op drop in blood pressure or oliguria Acute confusional state Stroke Diabetic hypoglycaemic states
How is an ACS diagnosed
2 out of 3
- suggestive history (s/s and risk factors)
- ECG changes (new ischaemia, q waves)
- troponin rise
ACS differentials
Cardiac - stable angina - pericarditis - myocarditis - aortic dissection - takotsubo cardiomyopathy Pulmonary - PE - pneumothorax - pleuritc chest pain Oesphageal - reflux/spasm - tumour
Investigations for ?ACS
ECG
CXR - may show cardiomeagly or widened mediastinum
Bloods
- FBS, U&Es, glucose, lipids, troponins and CK/LDH
Echo
- may show regional wall abnormalities
What troponin changes could indicate ACS?
Greater than x2 normal for diagnosis
Peak elevation is 12-24 hours after event
Differentiates angina and MI
What ECG changes could you expect in an MI?
STEMI - peaked T-waves - raised ST or new LBBB - after a few hours/days T-wave inversion and pathological q waves may develop NSTEMI (/unstable angina) - ST depression - T-wave inversion - non-specific changes - normal
Briefly describe the management of an STEMI
Oxygen
Aspirin 300mg and ticagrelor 180mg
Morphine 5-10mg IV (and anti-emetic)
PPCI (if available within 120 mins)
Fibrinolysis (PCI not available within 120 mins)
- later requires angiography or rescue PCI (if fibrinolysis unsuccessful)
Secondary management
When is a primary PCI indicated in MI?
Indicated in patients within 12 hours of symptom onset and within 120 minutes of first medical intervention
If not possible, the patient needs fibrinolysis followed by rescue PCI or angiogram
When is fibrinolysis/thrombolysis given in MI?
If the patient doesn’t meet the criteria for a PPCI, but is still within 12 hours of initial symptom
Given within 30 mins of admission
- alteplase (tPA)
DO NOT thrombolyse on ST depression alone, T-wave inversion alone or a normal ECG
What are the contraindications for thromboylsis?
Haemorrhage Ischaemic stroke AVM Cerebral malignancy Recent trauma/surgery GI bleeding Known bleeding disorder Aortic disorders
How are patients who present >12 hours after first symptoms managed in STEMI?
Patients who don’t get reperfusion therapy are given fondaparinux (LMWH) or unfractioned heparin
Breifly describe the acute management for an NSTEMI.
Oxygen Morphine Nitrates - GTN or tablets to dilate coronary artery Oral anti-platelets - aspirin 300mg Fondaparinux 25mg Second anti-platelet e.g. ticagrelor 180mg or clopidogrel 300mg IV nitrate (if pain continues) Oral beta-blocker e.g. bisoprolol Refer for angiography
Indications for angiography post-NSTEMI
Urgently (<120 mins after presentation) - ongoing angina and evolving ST changes - signs of cardiogenic shock - life-threatening arrythmias Early (<24h) - GRACE score >140 and a high risk patient Routine (within 72h) - lower-risk patient
What makes a patient high risk in ACS?
Over the age of 60y Previous stroke, TIA, MI or CABG Known coronary artery stenosis (greater than 50% in 2 or more vessels) Diabetes Peripheral artery disease Chronic kidney disease
What is the secondary prevention required post-MI?
Modify risk factors COBRA - Clopidogrel (at least 12 months) - Omega 3 (diet supplementation) - Bisoprolol (peripheral vasodilation reduces cardiac output) - Rampiril (reduces BP and risk of CKD) - Aspirin (at least 12 months) - Atorvastatin (regardless of cholesterol level)
What are the complications after/during an MI?
Cardiac arrest Cardiogenic shock Left ventricular failure Bradyarrhyhtmia Tachyarrhythmia Right ventricular failure Pericarditis Systemic embolism Cardiac tamponade Mitral regurgitation Ventricular septal defect Late malignant ventricular arrhythmia Dressler's syndrome Left ventricular aneurysm
