Acute coronary syndrome Flashcards
What is acute coronary syndrome?
Obstruction or occlusion of blood flow to the heart
a) STEMI
b) NSTEMI
c) Unstable angina
How might ACS present?
S: central/ retrosternal
O: at rest
C: tight, heavy, crushing
R: to jaw or left arm or back
A: not relieved by GTN - only opiates relieve pain
T: varies
E: none
S: ranges, stereotypically very severe
Associated symptoms: dyspnoea, sweating, N&V, impending doom
Differentials for MI?
- Pericarditis
- Aortic aneurysm
- Endocarditis
- Tamponade
- PE
- Anxiety
Pathophysiology of raised troponin
Cardiomyocytes die and release actin & myosin
Actin has troponin attached to it - it is released when the myocytes die
Troponin is an indicator of cardiac muscle death
Other causes of raised troponin
Cardiac causes
- Direct contusion of heart during trauma
- Aortic dissection
- HOCM
- Aortic stenosis/ regurg
- Rhabdomyolysis
- Myocarditis
Non-cardiac causes
- Renal failure
- PE
- Sepsis
- Burns
- Amyloidosis
- Stroke
- Subarachnoid haemorrhage
When do troponin levels peak following MI?
18-24hrs after and remain elevated for 10 days
Which chronic condition gives an elevated baseline troponin?
Renal failure
Types of MI based on cause
Type 1 = spontaneous MI due to primary coronary event: commonly a plaque ruptures leading to platelet aggregation and thrombus formation
Type 2 = secondary to ischaemia because o2 supply doesn’t meet demand e/g/ following a GI bleed or sepsis
Type 3 = diagnosed following sudden cardiac death
Type 4 = MI secondary to PCI
Type 5 = MI secondary to CABG
In which patients might ACS present atypically?
Women: atypical pain
Diabetics: may not have any pain
Elderly: only symptoms can be syncope + fatigue
What signs can be used as evidence of risk factors for ACS?
Complications of DM
HTN
Tar staining on fingers
Xanthelasma
Investigations for ACS
Bedside:
ECG
Bloods:
Troponin
Imaging:
Chest x-ray
Angiogram
Echo
ECG findings in ACS
NSTEMI: ST depression/ T wave inversion + angina-like pain = highly suggestive of ACS
STEMI: ST elevation is evidence of a significant coronary vessel being occluded
- Over time the ST segment reduces and T wve inversion occurs after a few days
- Months later pathological Q waves develop
Based on ECG when is a STEMI diagnosed?
>1mm elevation in 2 limb leads and >2mm elevated in 2 continuous chest leads
What is an anterior MI?
Usually due to occlusion of the left anterior descending artery aka widow maker
Anterior MI ECG
Proximal LAD infarct: ST elevation in V1-V6 + possibly lead 1 & aVL
Mid LAD: ST elevation in V3-V6
ECG in hypokalaemia?
Large U wave - looks like a second T wave
