NBRC Registered Respiratory Therapist (RRT) Exit Practice Exam

Which ECG finding is most associated with a myocardial infarction?

Depressed T waves Elevated ST segment Normal QRS Significant Q waves

Correct Answer:

Significant Q waves

Explanation:

Pathologic Q waves reflect irreversible myocardial necrosis from an infarction. When tissue dies, the electrical vectors change in a way that produces a deep, wide Q wave in the leads over the affected area. These waves persist as a scar and serve as a lasting marker that an infarct has occurred. While ST-segment elevation signals acute injury and depressed T waves indicate ischemia, they are not the enduring sign of infarction. A normal QRS complex would not fit MI. Therefore, significant Q waves are most closely associated with myocardial infarction.

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