Regarding ACS which of ONE the following statements is TRUE?
Answer: C: The ECG is the only investigation required to select a patient for emergency reperfusion. An echocardiogram may assist in decision making in difficult or less clear cut cases, looking for wall motion abnormalities in the area suggested by ECG changes. A negative troponin excludes a myocardial infarction but does not exclude an ACS, although does reduce the risk, especially in a patient with a normal ECG who is aged <40 years and has no cardiac risk factors. Troponin takes 6–12 hours after the onset of pain to become positive. Consequently, an early troponin may be a false negative. The CXR adds little to most patients in the assessment of ACS, although it may be potentially useful where aortic dissection is a possibility. CXR cannot exclude thoracic aortic dissection and CT angiogram of the aorta is required for that purpose.
References:
Regarding ECG changes associated with ACS, which ONE of the following statements is TRUE?
Answer: B:
There are multiple mimics of STEMI including:
Up to 50% of AMI have normal or nondiagnostic ECGs. A clinical decision rule developed by Sgarbossa et al.Attempts to predict the likelihood of AMI in a patient presenting with ischaemic symptoms and LBBB. This rule consists of a scoring system based on:
Only 1–2% of patients presenting with ischaemic symptoms to the ED have a new or presumed new (not known to be old) LBBB. The first Sgarbossa criterion, ST segment elevation ≥1 mm that is concordant with the QRS complex, if present, seems to be the most specific in diagnosing AMI in those patients. However, the Sgarbossa criteria have a limited sensitivity in diagnosing AMI in patients with LBBB. In clinical practice, because of their low sensitivity, these criteria may not be helpful (any diagnostic test/criteria should be highly sensitive to diagnose a critical condition such as AMI).
Patients presenting with ischaemic-sounding chest pain and ST segment elevation of ≥2 mm in 2 or more contiguous chest leads and ≥1 mm in the limb leads meet reperfusion criteria.
Regarding myocardial infarction, which ONE of the following statements is TRUE?
Answer: D: Posterior myocardial infarction is rarely isolated, and is usually associated with inferior or lateral wall infarction. It can be subtle and presents as ST segment depression in V1–V4. It is associated with RV infarction and failure. Anterior or anterior septal infarction is associated with ST elevation in V1–V4 and is the most common STEMI, with the worst prognosis. Lateral infarction is associated with ST elevation in leads 1, aVL and V5 and V6, and is due to occlusion of the left anterior descending (LAD) or circumflex arteries, while inferior AMI is manifested by ST segment elevation in leads II, III and aVF and is less common than anterior or anteroseptal AMI (see table below).
LOCALISATION OF MYOCARDIAL INFARCTION USING THE ECG:
Regarding contraindications to thrombolysis in STEMI, which ONE of the following statements is TRUE?
Answer: D: Chest pain with new neurology suggests aortic dissection, which is an absolute contraindication to thrombolysis. Absolute contraindications include those illnesses that increase bleeding risk and those conditions that increase the risk of intracranial haemorrhage. Some authors and manufacturers of tenecteplase do not differentiate between absolute and relative contraindications.
Absolute contraindications include:
Relative contraindications include:
Regarding reperfusion therapy in AMI, which ONE of the following is TRUE?
Answer: A: The CAPTIM trial, conducted in France, has suggested that prehospital thrombolysis given within 2 hours of symptom onset has better outcomes than percutaneous coronary intervention (PCI) and had equivalent outcomes with PCI if given within 4 hours.
PCI is the reperfusion treatment of choice for cardiogenic shock associated with AMI.
Tenecteplase has a higher risk of intracranial haemorrhage than streptokinase. Thrombolysis has a higher risk of bleeding-related adverse effects in females (because they generally weigh less), the elderly and patients with hypertension. The number needed to treat (NNT) to save a life for inferior STEMI is approximately 100–120.
Click to expand