ECG Challenge: Recurring Chest Pain in the Hospital

Philip J. Podrid, MD

Disclosures

September 11, 2019

The correct diagnosis is normal sinus rhythm, acute transmural anterior wall myocardial infarction.

Figure 2. Courtesy of Dr Podrid.

Discussion

The rhythm is regular at a rate of 90 beats/min. A P wave occurs before each QRS complex (+) with a stable PR interval (0.16 sec). The P wave is positive in leads I, II, aVF, and V4-V6. This is a normal sinus rhythm.

The QRS complex duration (0.08 sec) and morphology are normal. The axis is normal between 0° and +90° (positive QRS complex in leads I and aVF). Of note, hyperacute T waves are tall and, most important, symmetric in leads V3-V5. The normal T wave is asymmetric, with a slower upstroke and faster downstroke (as can be seen in V2). The hyperacute T wave is symmetric—ie, it has an upstroke and downstroke that are the same. This is the first ECG change of an acute transmural (ST segment elevation) myocardial infarction (STEMI) of the anterior wall.

The hyperacute T waves result from local hyperkalemia. The lack of oxygen and inability to resynthesize ATP causes loss of ATPase activity, which in turn compromises cell membrane integrity, and potassium leaks out from the cell. Because there is no blood flow into or out of the infarcted area, the potassium builds up, causing local hyperkalemia.

The QT/QTc intervals are 280/340 msec.

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