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MCQ – 89168

amit18289

Question

A 68-year-old man with a history of diabetes, hypertension, and hyperlipidemia are transported to the hospital via ambulance, complaining of crushing substernal chest pain. Emergency medical services personnel report that ST segments are >2 mm elevated in multiple anterior leads. Which of the following electrocardiographic findings is LEAST likely in this patient?
A.  Hyperacute T waves in the precordial leads
B.

ST-segment depression in leads III and aVF
C.

Shortened QT interval
D.

New right bundle branch block
Show Answer

Correct Answer � C

Explanation

Ans. C

· Early recognition of myocardial infarction (MI) is critical to take full advantage of emergent percutaneous revascularization or fibrinolytic therapy.

· The earliest electrocardiographic finding in acute ST-elevation MI is ST-segment elevation and hyperacute (tall, positive) T waves overlying the affected region of the myocardium.

· Reciprocal ST-segment depressions are often noted in leads overlying the opposite cardiac territories.

· In the absence of reperfusion therapy, T wave inversions become evident in the leads overlying the region of infarction over a matter of hours, accompanied by Q wave development.

· In the case of an anterior Q wave MI, the early ST-segment deflections become apparent in the anterior precordial leads, whereas ST-segment depressions are often present in the inferior leads.

· Acute infarction affecting portions of the conduction system may produce a new bundle branch block.

· In a patient with a convincing history of prolonged ischemic chest discomfort, a new LBBB is an acceptable criterion of acute infarction.

· A shortened QT interval is typical of hypercalcemia, not acute MI.

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