ACS - definition
Refers to a spectrum of acute myocardial ischaemia and/or infarction. Decreased blood flow in the coronary arteries such that part of the heart muscle is unable to function properly or dies. 3 conditions:
- unstable angina
- NSTEMI
- STEMI
Stable vs Unstable Angina
- Stable angina = at least 70% stenosis; chest pain only on exertion (supplies tissue at rest but heart needs to work harder on exertion)
- Unstable angina = usually rupture of plaque with thrombosis -> subendocardial ischaemia. Pain at REST
ACS - cardiac tissue involvement
- UA = subendocardial ischaemia
- NSTEMI = subendocardial infarction (20-40 min after onset)
- STEMI = transmural infaction (3-6 h after onset)
Cardiac biomarkers and ECG changes
UA - no changes in cardiac markers
- ECG may be normal or have changes (ST depression, T wave inversion
NSTEMI - elevated cardiac markers
- ECG changes: ST depression, T wave inversion
STEMI - elevated cardiac biomarkers
- ECG changes: ST elevation of at least 1 mm in 2 or more contiguous leads, may have new LBBB or pathological Q waves
Cardiac biomarkers in ACS
- Troponins (I and T): increase 3-12h from onset, peak at about 24-48 h and overall last 10-14 days
- CK-MB: rises after 3 h, peaks at about 24 h and lasts up to 72 h (more useful to determine re-infarction)
- myoglobin: first one to rise so useful for rapid Dx
ACS - risk factors
- Increasing age
- Gender (male for STEMI, female for UA)
- Diabetes
- Smoking
- Hypertension
- Hx of coronary artery disease
- Hyperlipidaemia
- PVD
- CKD
- Obesity
- Inflammatory conditions e.g. RA
What is type 2 MI and some causes?
MI not due to atheroma
- Supply and demand mismatch – cardiac muscle not receiving enough oxygen, often due to subendothelial tissue hypoxia – better prognosis than type 1 MI. Causes:
- Anaemia
- Hypoxia
- Shock
- Tachyarrhythmia
- Bradyarrhythmia
What is type 3 MI?
Type 3 MI: sudden cardiac death due to thromboembolism (no time to measure cardiac enzyme therefore classified as type 3 MI as unknown if they had previous atheroma)
UA - presentation
- increasing frequency of chest pain (several times a day, instead of occasionally)
- increasing severity of chest pain (decreasing levels of activity needed to trigger pain and may occur at rest)
- retrosternal pressure or heaviness radiating to jaw, arm, or neck that is improved by nitrates
- dyspnoea
- 4th heart sound (Indicates reduced myocardial relaxation due to ischaemia)
Acute MI - presentation
- central crushing chest pain (sensation of tightness, heaviness, aching, burning, pressure, or squeezing)
- diaphoresis, pallor
- dyspnoea
- N and/or V
- dizziness or light-headedness
- weakness and anxious
- tachycardia
- may have S3 or S4 heart sounds
Rarer causes of MI
- Aortic dissection – tearing pain that radiates to the back, different bp in the different arms, widening of mediastinum, risk of pericardial effusion and tamponade; worst at onset, then lingering pain with time
- Coronary artery spasm
- Oesophageal rupture - excessive retching, vomiting
- Pericarditis – saddle shaped ST elevation, relieved by learning forward; can have viral prodrome
ACS - investigations
- ECG
- cardiac biomarkers (tropinin, CK-MB +/- myoglobin)
- FBC (normal or low Hb)
- U+Es / electrolytes (usually normal)
- blood glucose
- lipid profile (normal or high total cholesterol and LDL)
- coagulation profile (should be normal)
- CXR (excludes HF, PE, aortic dissection, etc)
- consider echo (regional wall motion abnormalities)
ACS - criteria for hospital admission
Suspected acute coronary syndrome (ACS), who:
- Have current chest pain
- Have signs of complications (such as PE)
- Are pain-free, but have had chest pain in the last 12 hours and have an abnormal ECG
- A recent history of ACS, and they develop further chest pain.
Stable angina - treatment
not ACS
(The first-line investigation recommended by NICE is contrast-enhanced CT coronary angiogram)
- GTN spray (for use before performing activities known to cause symptoms of angina)
- BB or CCB
OR either one of:
a long-acting nitrate (isosorbide mononitrate)
Nicorandil
Ivabradine
Ranolazine - antiplatelet treatment (low dose aspirin - 75 mg daily)
- statins
What to give to people with angina and:
- stroke
- diabetes
STROKE
clopidogrel instead of aspirin
(long term ischaemic stroke Rx also includes warfarin)
DIABETES
consider adding ACEi
ACS - immediate management
IMMEDIATE
- IF SATS < 94%: Supplemental Oxygen - use a simple face mask. Adjust the flow rate to 5–10 L/min to achieve a target SpO2 of 94–98%.
- Treat pain with sublingual glyceryl trinitrate (GTN spray) and/or opioid (for example IV diamorphine 2.5 mg to 5.0 mg); also consider metoclopramide
- Give aspirin 300 mg*. Send a written record with the person that aspirin has been given.
- Take a resting 12-lead ECG. Send the results to the hospital
*chew for 30 seconds, then swallow
UA - further management (after MONA)
- antiplatelet therapy (clopidogrel or prasugrel or ticagrelor)
- BB or CCB
- anticoagulant (heparin -unfractionated- or a low molecular weight heparin, or fondaparinux sodium)
- glycoprotein IIb/IIIa inhibitors (eptifibatide) for high risk pts
- consider ACEi if HTN persists after BB
- chest pain not resolved: consider IV nitrates
NSTEMI - further management (after MONA)
- antiplatelet therapy (clopidogrel or prasugrel or ticagrelor)
- BB or CCB
Assess need for invasive or conservative approach - risk stratification tool (such as GRACE) is used to decide upon further management. If a patient is considered high-risk or is clinically unstable then coronary angiography will be performed during the admission.
- Invasive:
PCI + anticoagulant (heparin -unfractionated- or a low molecular weight heparin, or fondaparinux sodium)
+/- glycoprotein IIb/IIIa inhibitors (eptifibatide) - conservative = anticoagulation only
STEMI - definitive management (haemodynamically stable)
PCI - gold standard
- performed within 90 min of diagnosis
- should also receive anticoagulant -> either heparin (unfractionated) or a LMWH (e.g. enoxaparin sodium) or bivalirudin to prevent clotting during the procedure
- no-reflow or a thrombotic complication -> glycoprotein IIb/IIIa inhibitors (eptifibatide)
> 90 min –> thrombolytic therapy
- alteplase or reteplase
- PCI after thrombolysis recommended in high-risk pts
- anticoagulation
For both cases (additional Rx):
aspirin, antiplatelet therapy (clopidogrel or prasugrel or ticagrelor), BB, statin, ezetimibe (if require additional lowering of LDL after statin)
STEMI - definitive management (haemodynamically unstable)
1st line- PCI
2nd line - coronary artery bypass graft (CABG)
+ anticoagulation
+ aspirin
+ antiplatelet
- no-reflow or a thrombotic complication -> glycoprotein IIb/IIIa inhibitors (eptifibatide)
What is PCI?
Percutaneous coronary intervention (PCI or angioplasty with stent)
- A catheter is fed via radial or femoral artery to the coronary artery for angiogram to locate the thrombus
- A deflated balloon attached to a catheter (a balloon catheter) is passed over a guide-wire into the narrowed vessel and then inflated to a fixed size.
- The balloon forces expansion of the blood vessel and the surrounding muscular wall, allowing an improved blood flow.
- A stent may be inserted at the time of ballooning to ensure the vessel remains open, and the balloon is then deflated and withdrawn.
ACS - lifestyle measures (2ary prevention)
Cardiac Rehabilitation Programme - exercise,
education, relaxation and emotional support
In addition to adequate control of HTN, DM, and hyperlipidaemia, risk-factor intervention includes:
- smoking cessation
- regular physical activity with 30 minutes of moderate-intensity aerobic activity at least 5 times/week
- a healthy diet (low salt intake, decreased intake of saturated fats, regular intake of fruit and vegetables)
- weight reduction
ACS - long term management (2ary prevention)
- low dose aspirin continued indefinitely (75 mg daily)
- clopidogrel (or alternative) for 12 months
- BB
- statin
- ACEi
Consider angiotensin II antagonist eg valsartan if intolerant to ACEi; consider aldosterone antagonist and anticoagulants (for high risk or recurrence only)
(remember CRABS = clopidogrel, ramipril, aspirin, BB, statin)
Other causes of acute chest pain (NICE)
- pulmonary embolism
- tension pneumothorax
- sudden-onset cardiac arrhythmia
- cardiac tamponade
- aortic dissection
- ruptured oesophagus
