Acute Coronary Syndrome and Acute MI Flashcards
Definition of acute coronary syndrome
Any sudden cardiac event suspected or proven to be related to a problem with the coronary arteries
How do the problems of an ACS arise?
Due to myocardial ischaemia
Definition of myocardial ischaemia
Reduction of blood supply of heart muscle
Definition of MI
Cell death due to ischaemia
Major vs minor MI
Major - complete coronary artery occlusion
Minor - partial (or transient complete) coronary artery occlusion
ECG initially then at 3 days in a complete coronary artery occlusion
Initially - ST elevation
3 days - Q waves
ECG initially then at 3 days in a partial coronary artery occlusion
Initially - No ST elevation
3 days - no Q waves
What are the ACS?
Unstable angina
MI (STEMI / NSTEMI)
Sudden cardiac death
What part of the heart is affected in a STEMI?
Q wave MI
Transmural MI
What part of the heart is affected in NSTEMI?
Non Q wave MI
Subendocardial MI
What does STEMI stand for?
ST elevation MI
What does NSTEMI stand for?
Non ST elevation MI
What does a completely occluded artery cause?
Ongoing myocyte death
Non cardiac causes of troponin rise
Pulmonary embolism
Sepsis
Renal failure
SAH
What is troponin?
A group of proteins that help regulate the contractions of the heart and the skeletal muscles
When does the heart release troponin into the blood?
Heart injury e.g. MI
Causes of MI
Coronary atherosclerosis
Coronary vasospasm
Coronary dissection
Embolism of material down coronary artery
Vasculitis of coronary arteries
Radiotherapy to chest causing fibrosis and stenosis of coronary arteries
Who often gets coronary dissection?
Younger, healthier females
Causes of coronary vasospasm
Cocaine
Triptans
5-FU (chemo)
Cardiac risk factors
Male Age Known heart disease High BP High cholesterol DM Smoker FH of premature heart disease
Diagnostic criteria for MI
- Detection of cardiac cell death by +ve cardiac biomarkers
- AND ONE OF
- symptoms of ischaemia
- new ECG changes
- evidence of coronary problem on coronary angioplasm or autopsy
- evidence of new cardiac damage on another test
Presentation of MI
Chest pain - radiating to neck / arm / jaw - may be described as a discomfort - severe pain Nausea Sweating SOB
Causes of chest pain
Cardiac - coronary artery disease - aortic valvular disease - pulmonary HTN - mitral valve prolapse - Pericarditis - idiopathic hypertrophic subaortic stenosis Pulmonary - PE - Pneumonia - Pleuritis - Pneumothorax Emotional - Anxiety - depression Vascular - aortic dissection Neural - herpes zoster MSK - costochondritis - Arthritis - muscular spasm - bone tumour GI - ulcer - bowel disease - hiatus hernia - pancreatitis - cholecystitis
How long do the symptoms of typical angina last of an ACS?
> 20 mins
What would you do if someone presented with ACS chest pain?
- ECG
- ST elevation = STEMI
- No ST elevation……. - After 3 - 4 hours
- Troponin
- if NO - unstable angina, if YES - NSETMI - After 1 - 2 days
- From NSTEMI if Q waves - Qw MI, if no Q waves the NQMI
Treatment for STEMI
Reperfusion - Primary PCI - Pharmacological Angioplasty Thrombolysis
How does angioplasty work?
Expanded balloon in between plaque and the artery
Stent is deployed compressing the plaque
How does thrombolysis work?
Tenecteplase (TNK) given as a bolus
What is the risks of thrombolysis?
Bleeding
Who should thrombolysis not be given to?
Recent stroke Previous intracranial bleeding Caution if - recent surgery - on warfarin - severe HTN
In STEMI, what should be done if can get to cath lab in 2 hours and what if not?
Within 2 hours - Primary PCI
After 2 hours - Thrombolysis then transfer for PCI
Compared to STEMI, NSTEMI patients tend to be…..
Older
More likely to have had previous MI
More likely to have had previous CABG/PCI
May not have clear obvious coronary presentation
Investigations of suspected ACS
Serial ECGs
Bloods
What should be given if admitted with suspected ACS?
GTN
Opiates (e.g. morphine)
What are the antithrombotic drugs?
Heparin
LWMH
Fondaparinux
Example of ACEI
Ramipril
Risks of coronary angiography/angioplasty/stenting
Bleeding Blood vessel damage MI Coronary perforation Stroke Contrast nephropathy
What does CABG stand for?
Coronary artery bypass graft
Who gets CABG?
Three vessel disease
Left main stem disease
Disease not amendable to PCI
Complications of MI
Arrhythmia Cardiogenic shock Myocardial rupture Valve dysfunction due to papillary muscle dysfunction / rupture Acute VSD Death
Types of MI
Type 1 - 6
Type 1 MI
Spontaneous MI associated with ischaemia and due to a primary coronary event such as plaque erosion, rupture, fissuring or dissection
Type 2 MI
Imbalance of supply and demand of oxygen. Result of ischaemia
Type 3 MI
Sudden cardiac death including cardiac arrest, with symptoms of ischaemia, accompanied by new ST elevation or LBBB
Type 4a MI
Assosiated with PCI
Type 4b MI
Assosiated with verified stent thrombosis via angiography or autopsy
Type 5 MI
Assosiated with CABG
What would occlusion of R coronary artery cause?
Inferior MI
What would occlusion of left anterior descending coronary artery cause?
Anterior MI
What would occlusion of circumflex coronary artery cause?
Lateral MI
How do thrombolytic agents work?
Covert plasminogen to plasmin which lyses the clot by breaking down the fibrinogen and fibrin contained in the clot
Two categories of thrombolytic agents
Fibrin specific agents
Non fibrin specific agents
Examples of fibrin specific agents
Alteplase
Reteplase
Tenecteplase
Example of non fibrin specific agents
Streptokinase
Contraindications to thrombolytic agents
Prior ICH
Known structural cerebral vascular lesion
Known malignant intracranial neoplasm
Ischaemic stroke within 3 months
Suspected aortic dissection
Active bleeding or bleeding diathesis (excluding menses)
Significant closed head trauma or facial trauma within 3 months
If no evidence of STEMI, use the ACS treatment protocol, which involves….
Aspirin Ticagrelor/clopidogrel Fondaparinux/LWMH IV nitrate Analgesia BBs
Management to reduce the risk from NSTEMI
PCI CABG Aspirin Clopidogrel etc LWMH Fondaparinux Gllb/IIIa receptor blockers Statins BBs
How does clopidogrel work?
Inhibits ADP receptor activated platelet activation (ADP receptor antagonists)
Blocks activation of GP IIb/IIIa pathway
This complex is a receptor for fibrinogen, fibronectin and von WF. Activation of this is a final combination pathway for platelet aggregation and cross linking of platelets by fibrin
What is clopidogrel / ticagrelor always used in combination with?
Aspirin
What does LWMH stand for?
Low weight molecular heparin
Examples of LWMH
Enoxaparin
Dalteparin
Tinzeparin
Fondaparinux
How do glycoprotein IIb/IIIa receptor inhibitors work?
Integrin complex found on platelets
Receptor for fibrinogen aids in platelet activation
Platelet activation by ADP (blocked by clopidogrel) leads to a conformational change in platelet GPIIb/IIIa receptor that induces binding to fibrinogen
SIGN guidelines for treatment of ACS
- Immediately aspirin (300mg loading dose) and ticagrelor (180mg loading dose)
- Maintained on long term aspirin therapy
- Started on long term statin
- Maintained on long term beta blocker therapy
What should patients with unstable angina be started on?
Long term ACEIs
Patients with MI should be commenced on what within the first 36 hours?
Long term ACEI
Patients with MI complicated by LV dysfunction (ejection fraction < 40%) in the presence of either clinical features of HF or DM should be commenced on what?
Long term eplerenone therapy
What can happen to the lungs after an MI?
Flash pulmonary oedema can occur - after acute mitral valve regurg due to MI
Complete heart block following an MI indicates damage to which artery and why?
Right coronary artery
The AV node is supplied by the posterior interventricular artery which is a branch of the right coronary artery (in the majority). In the minority it is a branch of the left circumflex artery
What does persistent ST elevation after an MI indicate and what are the consequences of this?
Left ventricular aneurysm
Blood stagnates around the left ventricular aneurysm, thereby promoting platelet adherence and thrombus formation
Embolization of left ventricular thrombi can lead to embolic stroke or other systemic embolis
MI and driving regulations
If private vehicle - does NOT need to notify DVLA following PCI and can resume driving after 4 WEEKS
If group 2 license (bus or lorry) - MUST notify DVLA. May not drive for at least 6 weeks. Then DVLA can do further assessment after this time scale.
ECG changes for thrombolysis or PCI
ST elevation of > 2mm (2 small squares) in 2 or more consecutive anterior leads (V1 - V6)
OR
ST elevation of > 1mm (1 small square) in greater than 2 consecutive inferior leads (II, III, aVF, aVL)
OR
New LBBB
Reversible causes of MI
Hypoxia Hypovolaemia Hyperkalaemia Hypokalaemia Hypoglycaemia Hypocalcaemia Acidaemia Other metabolic disorders Hypothermia Thrombosis (coronary or pulmonary) Tension pneumothorax Cardiac tamponade Toxins
Management of a VT/VF cardiac arrest
A single shock followed by
1 mins of chest compressions
Adrenaline 1mg once they have restarted after the third shock and then every 3 - 5 mins (during alternative cycles of CPR)
Management of cardiac arrest if it was witnessed
Up to 3 quick successive shocks (stacked) rather than 1 shock followed by CPR
What should be given asap in asystole / pulseless electrical activity?
Adrenaline 1mg
What is the Framingham risk score?
Used to estimate the 10 year risk of a heart attack
Where would ECG changes occur in an anteroseptal MI? Which coronary artery would be involved?
V1 - V4
LAD
Where would ECG changes occur in an inferior MI? Which coronary artery would be involved?
II, III, and aVF
Right coronary
Where would ECG changes occur in an anterolateral MI? Which coronary artery would be involved?
V4-V6, I, aVL
LAD or left circumflex
Where would ECG changes occur in a lateral MI? Which coronary artery would be involved
I, aVL +/- V5 + V6
Left circumflex
Where would ECG changes occur in a posterior MI? Which coronary artery would be involved?
Tall R waves V1 - V2
Usually left circumflex
Also right coronary
What may also point to the diagnosis of an ACS on ECG?
LBBB
What are the only shockable rhythms?
VF
VT
What does a posterior MI cause on a 12 lead ECG?
ST depression NOT elevation
What does an inferior MI on ECG and a AR murmur raise suspicions of?
Ascending aortic dissection
How long does troponin stay raised for after an MI?
10 days
How long does creatine kinase stay raised for after an MI?
3 - 4 days
Which is best to measure if suspect a re-infarction a few days after the initial MI, creatine kinase or troponin?
Creatine kinase better for 4 - 10 days post original insult
Poor prognostic factors in ACS
Age Development (or history) of HF PVD Reduced systolic BP Killip class Initial serum creatinine conc. Elevated initial cardiac markers Cardiac arrest on admission ST segment deviation
What is the killip class?
System used to stratify risk post MI
Most common cause of death in a patient following an MI
Ventricular fibrillation
What can beta blockers reduce awareness of?
Hypoglycaemic episodes