Interpret the ECG shown in the figure below, which was obtained from a middle-aged adult. Are there DeWinter T waves in the chest leads shown in the figure? Is this patient about to occlude his proximal left anterior descending (LAD) coronary artery? Or does this patient have hyperkalemia? What is missing (that should never be missing)?

Interpretation: There is some baseline movement with slight artifact. The rhythm is sinus tachycardia at a rate of 160/minute. The PR interval is normal, and the QRS complex is narrow. All intervals appear to be normal. The axis is indeterminate, as QRS complexes are nearly isoelectric in virtually all limb leads. There is no chamber enlargement. Regarding Q-R-S-T Changes, there appears to be a Q wave in lead aVL, and transition is slightly delayed to between V4 to V5. The most remarkable findings on this tracing are the tall and peaked T waves, especially in leads V2 thru V4. In a patient with chest pain, this T wave appearance suggests ischemia or even impending proximal LAD occlusion (i.e., DeWinter T waves). There is even a suggestion of some J-point ST depression in leads V3, V4, and V5 prior to the steep rise in T wave ascent. On the other hand, in a patient predisposed to hyperkalemia, the T wave peaking seen here should prompt consideration of this electrolyte disturbance. That said, something is missing from this presentation!

Answer: No history was given. It turns out that this 12-lead ECG was recorded as part of an exercise stress test on an otherwise healthy and asymptomatic middle-aged man. The purpose of this test was to assess exercise capacity. There was no chest pain and no history of renal disease or other medical problems. Both peaked T waves and rapid-upslope ST segment depression are common normal findings during an exercise test.

Lesson To Be Learned: ECGs cannot be intelligently interpreted in a vacuum. If told that this patient was having new-onset chest pain we would wonder why his heart rate is so fast, and we would clearly be concerned that the prominent T wave peaking might be ischemic or a DeWinter T wave equivalent. We would check serum potassium values as part of our evaluation, especially if the patient had any factors potentially predisposing to hyperkalemia.

This patient had excellent exercise capacity for his age. His exercise test was entirely normal, and he was cleared to perform vigorous aerobic activity. No laboratory testing was done (as this was not necessary).

ECG Review 071515
Figure: ECG obtained from a middle-aged man.