Regarding chest pain, which ONE of the following statements is TRUE?
Answer: A: A detailed history obtained from the patient regarding the nature of chest pain is important for the diagnosis and risk stratification. The positive likelihood ratios (LRs) have been determined for various descriptions of chest pain. The positive LR for pain radiating to the right arm or shoulder as an indicator of myocardial infarction is 4.7 compared with LR of 2.3 for pain radiating to left arm. The positive LR for pain radiating to both arms and shoulders is 4.1. Burning or indigestion pain can be associated with ACS (LR 2.8), while pain reproducible by palpation and described as pleuritic, sharp or positional does not exclude ACS or AMI.
Regarding investigations for chest pain, which ONE of the following statements is TRUE?
Answer: C: Approximately half of the patients with AMI will have an initial ECG showing a new ST segment elevation ≥1 mm in two contiguous leads. Its positive predictive value for diagnosis of AMI has been described as >90%.
Patients with an elevated troponin have a worse 2- and 28-day prognosis compared with patients without an elevated troponin.
Compared with conventional troponin assays, with the use of new high-sensitive troponin assays (both TnT and TnI), troponin can be detected at much lower levels. Consequently, these superior performing high-sensitivity assays have increased sensitivity in early detection of AMI. However, these increased sensitivities have been achieved at the expense of reduced specificities (table below).
SENSITIVITY AND SPECIFICITY IN THE DIAGNOSIS OF AMI USING HIGH-SENSITIVITY TROPONIN ASSAYS (WHEN A CUT-OFF VALUE OF 0.07 MCG/L OR 99TH PERCENTILE IS USED)
In the absence of ischaemic heart disease, troponin can be elevated in a range of non-ischaemic pathologies. This should be considered when interpreting troponin results. Troponin can be elevated in the following non-ischaemic conditions including:
Exercise stress testing is a functional test that is prognostically useful in predicting adverse events for coronary artery disease (CAD) despite its limited sensitivity and specificity in diagnosing CAD. It is useful for risk stratifying low to intermediate risk patients.
Regarding risk stratification for patients with suspected non-ST segment elevated ACS (NSTEAC), which ONE of the following statements is TRUE?
Answer: A: TIMI score has been validated as a predictor of adverse outcomes (subsequent myocardial infarction, mortality, arrhythmia) and the need for early invasive management for NSTEAC syndrome. TIMI refers to the name of the research organisation that conducted the trials.
Age, diabetes and previous aspirin use are all variables that need to be considered in risk stratification of NSTEACS. Patients with a low TIMI score still have considerable risk for adverse events, with a score of 0–1 having a risk of up to 4.7%.
TIMI score calculations (1 point for each factor present):
Table below shows the percentage of risk at 14 days of mortality due to all causes, new or recurrent MI or severe recurrent ischaemia requiring urgent revascularization.
Regarding ST elevation myocardial infarction, all of the following are true EXCEPT:
Answer: B: ST elevation in leads II, III and aVF suggests an inferior infarction that may involve the right coronary or circumflex arteries, as can posterior infarctions. Posterior infarction may also be caused by occlusion of the circumflex artery in patients with dominant left-sided circulation. Inferior and posterior AMI may be associated with RV infarction. Posterior AMI are associated with ST segment depression in V1 and V2 and ST segment elevation in posteriorly placed leads. One of the earliest markers of an inferior AMI may be ST depression in lead aVL.
Regarding the ECG in ST segment elevation myocardial infarction, which ONE of the following statements is TRUE?
Answer: A: ST segment elevation in aVR in a patient with ischaemic-sounding chest pain is a marker for proximal left system disease, which has a mortality of up to 70%, and should not be treated as a non-STEMI.
Posterior STEMI is often difficult to diagnose. It is characterized by:
Wellen’s syndrome is characterised by abnormal T wave inversion or biphasic T waves, especially in leads V2–4. These changes may be a marker of proximal left main disease, particularly in patients with ischaemic-sounding chest pain.
ECG criteria for reperfusion are:
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