Master the board step 3

Cardiology
A patient admitted 5 days ago for a myocardial infarction has a new episode of
chest pain. Which of the following is the most specific method of establishing the
diagnosis of a new infarction?
a. CK-MB
b. Troponin
c. Echocardiogram
d. Stress testing
e. Angiography
Answer: A. The CK-MB level should return to normal 2–3 days after a myocardial
infarction. If a reinfarction has occurred, the level will go back up again 5 days later,
while the troponin level will still be up from the original infarction. Angiography can
detect obstructive, stenotic lesions but cannot detect myocardial necrosis. Stress testing
should never be performed if the patient is having current chest pain; chest pain is a
reason to stop a stress test. Echo will show decreased wall movement, but this could
have been present from the previous cardiac injury.
Acute Coronary Syndrome (ACS)
The definition of acute coronary syndrome (ACS) is as follows:
··
Causes acute chest pain
··
Can be with exercise or at rest
··
Can have ST segment elevation, depression, or even a normal EKG
··
Not based on enzyme levels, angiography, or stress test results
··
Based on a history of chest pain with features suggestive of ischemic
disease
Treatment
Aspirin
The best initial therapy for all cases of ACS is aspirin. Aspirin can be administered
orally or chewed and absorbed under the tongue. It has an instant effect
on inhibiting platelets. Aspirin alone reduces mortality by 25 percent for acute
myocardial infarction and by 50 percent for “unstable angina,” which may
become a non-ST segment elevation myocardial infarction (NSTEMI). Nitrates
and morphine should also be administered in acute coronary syndromes, but
they do not lower mortality. Oxygen has no benefit if the patient is not hypoxic.
Clopidogrel or ticagrelor is added to aspirin for all patients with acute myocardial
infarction. Prasugrel is given only when angioplasty is done.
Prasugrel, clopidogrel,
or ticagrelor is added
to everyone getting
angioplasty and a stent.
These meds inhibit ADP
activation of platelets.
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