Acute coronary syndromes (ACS) Flashcards
What is a typical history of a patient with acute coronary syndrome?
(symptoms)
- Sever crushing, gripping or heavy chest pain lasting longer than 20 minutes
- Not relieved by 3x GTN sprays at 5 minute intervals
- Radiates to the left arm, neck or jaw
- Associated dyspnoea, nausea, fatigue, sweatiness and palpitations in the elderly or diabetics, who can present later with a variety of symptoms
What are the clinical features of ACS?
(on examination)
Can be variable
- Sympathetic activation: tachycardia, hypertension, pallor, sweatiness
- Vagal stimulation: bradycardia, vomiting
- Myocardial impairment: hypotension, narrow pulse pressure, raised JVP, basal crepitations, 3rd heart sound
- Tissue damage: low grade pyrexia
Later a pericardial rub and peripheral oedema may develop, or pansystolic murmer due to papillary muscle rupture/ventriculo-septal defect
What are differential diagnosis of central chest pain from ACS?
(not an objective)
Cardiac:
- Coronary artery spasm
- Pericarditis/myocarditis
- Aortic dissection
Non-cardiac:
- PE
- Pneumothorax
- Oesophageal disease
- Mediastinitis
- Costochondritis
- Trauma
What does the spectrum of acute coronary syndromes cover?
ST-segment elevation myocardial infarction (STEMI)
Non-ST-segment elevation myocardial infarction (non-STEMI)
Unstable angina (UA)
What pathology do all acute coronary syndromes share?
- Atheromatous plaque formation in the coronary arteries
- Fissuring/ulceration of the plaque leading to platelet aggregation
- Localised thrombosis, vasocontriction and distal thromboembolism
- Myocardial ischaemia
What is unstable angina?
(aka crescendo angina)
- Angina occuring at rest, or sudden increased frequency/severity of existing angina
- Pathologically caused by fissuring of plaques, thus there is a risk of subseuent total vessel occlusion and progression to acute MI
What is the an acute myocardial infarction?
What are the two different types?
- Occurs followinf full arterial occulsion, with different patterns
- The diagnosis of MI requires elevations in serum cardiac troponin levels, with additional categorisation based on ECG changes:
- ST elevation = STEMI
- No ST elevation = NSTEMI (ECG often shows T wave inversion or ST depression)
NSTEMI occurs by developing a complete occlusion of a minor coronary artery or a partial occlusion of a major coronary artery previously affected by atherosclerosis.
STEMI occurs by developing a complete occlusion of a major coronary artery previously affected by atherosclerosis. This causes a full thickness damage of heart muscle.
What is the time course of an MI?
(not an objective)
0-12 hours
12-24 hours
24-72 hours
3-10 days
10 days - months
- 0-12 hours: infarct not visible, loss of oxidative enzymes
- 12-24 hours: infarct pale and blotchy , intercellular oedema
- 24-72 hours: infarcted area excites acute inflammatory response, with dead area soft and yellow with neutophilic infiltration
- 3-10 days: organisation of infarcted area by vascular granulation tissue
- 10 days-several months: collagen deposition, infarct replaced by collagenous scar
How does an ECG and serum troponin establish the diagnosis of an ACS?
STEMI:
- ST segment elevation, troponin elevated.
- Troponin is released at 4-8 hours and peaks at around 24 hours. dectectable for 10 days
- A release of CK-MB may be an earlier enzyme sign.
NSTEMI:
- No ST segment elevation, troponin elevated.
Unstable angina:
- No ST segment elevation, troponin normal.
What is the management of unstable angina and NSTEMI?
(normal A-E)
(asses patient using GRACE score)
BROMANCE
- Beta-blocker
- Reassurance
- Oxygen
- Morphine
- Aspirin
- Nitrates/GTN spray
- Clopidigrel
- Enoxaparin
What is the management of STEMI?
MONA
- Morphine
- Oxygen
- Nitrates (GTN spray)
- Aspirin
Percutaneous coronary intervention (PCI) is gold standard treatment if available in a timely fashion: door to ballon in 90 minutes, patient transfer advised if intervention can occur within this window
GRACE score as well
What if PCI are contra-indicated for a STEMI?
What are the conta-indications?
Thrombolysis is indicated if PCI not available or there are significant co-morbidities
What are contra-indications for thrombolysis?
- haemorrhagic stroke at any time
- ischaemic stroke within 6 months
- CNS damage or neoplasm
- recent trauma (3 weeks)
- GI bleed within last month
- known bleeding disorder or aortic dissection.
- Relative contraindications include pregnancy, liver disease, endocarditis, traumatic CPR, oral anticoagulant therapy, refractory hypertension.
Describe the difference in prognosis between STEMI, non-STEMI and unstable angina with respect to mortality and morbidity
6 month mortality in the GRACE registry was 13% for NSTEMI and 8% for UA.
1 month mortality in a community STEMI may be as high as 50%, with 50% of these deaths occurring within 2 hours. Early death may be due to arrhythmia. Of those who reach hospital, 80% survive up to 28 days. Prognosis is worse for anterior infarcts than inferior. Morbidity is likely to be related to the level of ischaemia and myocardial damage sustained.
What is the GRACE score for ACS?
Takes into account age, heart rate, blood pressure, class of CHF, renal function, ST segment changes, troponin elevation and whether there was an arrest at admission to give a mortaily risk at various time intervals (usually one for 6 months)
