CBL_1 ACS Flashcards
What Acute Coronary Syndrome (ACS) refers to (in terms of presentation)?
Acute Coronary Syndrome ACS refers to acute chest pain of cardiac origin
What underlying conditions may ACS refer to? (6)
- ST elevation Myocardial infarction (STEMI)
- Non ST elevation Myocardial Infarction (NSTEMI)
- Unstable angina (UA)
There are also
- chronic angina
- undiagnosed CHD
- atheroma
How to differentiate STEMI from Non-STEMI?
ST elevation Myocardial infarction (STEMI): cardiac enzyme release and ST elevation on the ECG
Non ST elevation Myocardial Infarction (NSTEMI): cardiac enzyme release
What are characteristics on Ix of unstable angina?
Unstable angina (UA): no cardiac muscle necrosis -> ECG changes reverse; no cardiac enzyme release
BP targets for secondary prevention
Secondary prevention - treated hypertension targets
- below 140/90 mmHg if aged under 80 years
- below 150/90 mmHg if aged 80 years and over
Normal lipids/ cholesterol results
Total cholesterol < 5 mmol/l
Triglycerides < 2 mmol/l
HDL cholesterol > 1 mmol/l
LDL cholesterol < 3 mmol/l
What’s the normal glucose range?
- Fasting; normal: <5.5 (> 7.0 = diabetic)
- oral glucose tolerance; normal: <7.8 (>11.1 = diabetic)
Patient with not known angina and central chest pain
What to do?
Call 999
Patient with known angina and central chest pain
What to do?
- Use GTN spray -> repeat after 5 mins if pain hasn’t gone
- If after further 5 mins, pain hasn’t gone -> call 999
Causes of secondary MI
Secondary MI = not due to atheroma
- anemia
- hypoxia
- shock
- tachyarrhythmia
- bradyarrhythmia
Possible causes of cardiac chest pain
- reduction of oxygen supply into the myocardium
- aortic dissection
- coronary artery spasm
- oesophageal rupture
- pericarditis
What are the features of cardiac chest pain?
Ischaemic symptoms e.g. chest pain with radiation to arm/ jaw
Possible associated features with chest pain (in ACS) (2)
- vomiting
- sweating
Why is there vomiting and sweating in MI?
visceral pain -> pain from nociceptors -> commonly refer in a diffuse way over a number of dermatomes with autonomic features
Who may have no pain in MI?
- elderly
- diabetics
This is due to autonomic nervous system degeneration
Aspirin MoA
Aspirin is “anti-platelet aggregation”-> inhibits cyclo-oxygenase (COX) enzyme and so preventing production of certain prostaglandins and thromboxane production, all of which encourage platelet aggregation -> sp less platelet aggregation (less clot is formed)
What to do if a patient has MI in GP surgery?
- Give aspirin 300mg
- Call 999 and do ECG while waiting for the ambulance
- Record keeping: note with med and dose/time administrated + PMH (with referral to the hospital)
- Help: defibrillator equipment should be kept ready + extra staff should attend the patient
- Give oxygen if sats <95%
- GTN spray (if suspicion of angina and if not too hypotensive BP systolic >90 mmHg)
Investigations in ACS
- IV access
- Serial ECGs showing ST elevation and this can relate to sites of damage , changes in rhythm, new Q waves or LBBB
- Serial Troponins: Troponin is a protein released from damaged cardiac myocyctes
- CXR for LVF and cardiomegaly and differentials
- oxygen (sats)
What are enzymes and markers used in Ix of possible MI?
- Troponin I or T rises in 3-12 hours of chest pain, peaks at 24-48 and is the baseline at 5-14 days so do at presentation and 10-12 hours after chest pain started. Amount released relates to size of MI
Other enzyme biomarkers are not as sensitive or specific:
- Myoglobin rises first, creatinine kinase in about 3 hours, also WCC can rise, ESR and CRP can rise and BNP may rise
What happens in PCI?
Percutaneous coronary intervention (PCI)
- non-surgical procedure used to treat stenosis of the coronary arteries
- after accessing the blood stream through the femoral or radial artery, the procedure uses coronary catheterization to visualise the blood vessels on X-ray imaging
- an interventional cardiologist can perform a coronary angioplasty, using a balloon catheter in which a deflated balloon is advanced into the obstructed artery and inflated to relieve the narrowing
- certain devices such as stents can be deployed to keep the blood vessel open
2 first steps of PCI
- Aspirin 300mg given in primary care
- One of three oral ADP receptor antagonist antiplatelet medications given in secondary care. Clopidogrel initially as a loading dose or
prasugrel or ticagrelor
*the last two medications work more quickly at 30 minutes rather than clopidogrel at 3–4 hours.
Why do we give so many anti-platelet and anticoagulation meds to the patient with PCI?
Patient receives a number of anticoagulants to improve perfusion and prevent further thrombus; undergoes angioplasty with stent insertion; then antiplatelet medication to take home
What further meds a patient undergoing PCI is given in a catheter lab?
3. In the catheter lab other agents such as unfractionated heparin given (factor 10 inhibitor and antithrombin) or bivalirudin (f2 thrombin inhibitor) to prevent clotting during the procedure
4. A minority of patients get another antiplatelet group, the GP2B/3A platelet receptor antagonists, GPIs, which are abciximab or eptifibatide or tirofiban
Step 5 and 6 in PCI (after meds are given)
- A catheter is fed via radial or femoral artery to the coronary artery for angiogram
6. The thrombus in the coronary artery may be aspirated and then balloon angioplastied with a stent being expanded in the previously occluded area
What is the compilation of stent insertion in PCI?
Stent restenosis: the recurrence of abnormal narrowing of an artery or valve after corrective surgery
Bare metal stents have a 20% restenosis rate by re-endothelialisation at six months and so drug eluting stents were produced to reduce this
What is offered to a patient if PCI did not work or to the patient with the extensive disease?
Coronary artery bypass grafting (CABG)
What meds do patients with unstable angina/NON-STEMI MI do receive in the hospital?
Initially:
- high dose aspirin and clopidogrel
- they may get O2
- morphine and metclopramide
on the CCU they receive
- statin
- B-blocker
- LMWH
- ACEI
What score is used to determine if a patient with unstable angina/ non-STEMI MI needs an angiogram?
- GRACE score to determine if they can go home on therapy or require an angiogram
- It stratifies patients into low risk (<1.5%) up to highest risk (>9%) of death at six months post ACS and uses this to suggest therapy
What GRACE score is used for?
Grace Score is used to predict patient mortality at 6 months and helps decide therapy and management
What would you expect to be in the Grace score to predict a poor outcome after a MI?
- advancing age
- severity of heart failure
- pulse rate
- systolic blood pressure
- renal function
- ST changes on ECG
- raised troponins
- cardiac arrest at admission
What meds do most patients receive after hospital admission for MI?
Most patients receive aspirin and clopidogrel (dual antiplatelet therapy/ DAPT)
- In addition for angina - patients may have nitrates
- For prognosis improvement: B blocker (bisoprolol), ACEI (ramipril) and DAPT 12 months and then assess as probably only need one antiplatelet at that stage
What meds do most patients receive after hospital admission for MI?
- aspirin (lifelong) + copidogrel/ticaglerol (12 monrs)
- Statin
- B-blocker (Bisoprolol)-> to reduce myocardial demand (continued for 12 months or lifelong if LV dysfunction)
- ACE inhibitor (Ramipril) -> prevents adverse cardiac remodeling
- GTN spray (when required)
- Aldosterone antagonist (eplerenone) if LV is =<40%
Advise: *BP control, lifestyle modification, cardiac rehabilitation and smoking cessation
Initial steps in management of ACS (2 x mnemonics)
A B C D E approach if critically ill
M - morphine IV (+ metoclopramide IV)
O - oxygen (if sats below target 94%-98%)
N - nitrate
A - aspirin - loading dose 300mg; then 75mg
C - clopidogrel
Regions on ECG and possible MI location
The classic triad of Dressler’s syndrome
- Pericarditis
- Fever
- Pericardial effusion
*seen 2-10 weeks after MI
Features of Dressler’s syndrome
What’s physical examination like?
Features include:
- central stabbing chest pain (worse on inspiration and lying flat)
- fever and lethargy
- pericardial and pleural effusions
Examination is often irrelevant, although a pericardial rub might sometimes be heard
What Dressler’s syndrome is a result of?
It is thought to be autoimmune condition secondary to the generation of the new myocardial antigens after an MI. they have a raised ESR secondary to the inflammation process.
Management of Dressler’s syndrome
- usually settles with NSAIDS and analgesia
- sometimes steroids are needed
What anti-coagulation start in NSTEMI for a short-term?
Fondaparinux or LMWH or Heparin for 5 days
Are glycoprotein IIb/IIIa inhibitors often used?
Not, used in very selective patients only
Examples of IIb/IIIa: Abciximab, eptifibatide, tirofiban
What’s gold standard reperfusion therapy for AC?
PCI (Percutaneous Coronary Intervention)
When is thrombolysis (as Rx for ACS) used? (indications)
It’s rarely used (many contraindications related to bleeding risk)
- if PCI unavailable within 2 hours
- STEMI in two contiguous ECG leads
- new LBB
Contraindications for thrombolysis
Related to bleeding risk
- active internal bleeding
- bleeding disorder
- aortic dissection
- stroke
- surgery/trauma <2 weeks
- Hx of CNS bleed/aneurysm/neoplasm
- GI bleed <1 month
Indications for PCI
Any ACS:
- SEMI (any ST elevation or new LBBB)
- NSTEMI
- Unstable angina
Contraindications: significant comorbidities
*PCI is a gold standard Rx for ACS
MoA of unfractionated heparin
Factor X inhibitor and anti-thrombin
Clopidogrel MoA
Antiplatelet -inhibits ADP binding to its platelet receptor
Bivalirudin MoA
Reversible direct thrombin (factor II) inhibitor
Class: thrombin inhibitor
Class and MoA of Fondaparinux
Fondaparinux
class: anti-thrombotic agent
MoA: activation of antithrombin III, which in turn potentiates the inhibition of coagulation factors Xa
Enoxaparin
class
MoA
Enoxaparin
Class: LMWH
MoA: Activates antithrombin III, which in turn potentiates the inhibition of coagulation factors Xa
