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
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| B. |
ST-segment depression in leads III and aVF
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| C. |
Shortened QT interval
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| D. |
New right bundle branch block
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Show Answer
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Correct Answer � C
Explanation
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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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