Subtle Electrocardiographic Abnormalities

A 72-year-old diabetic, hypertensive man presents with waxing and waning episodes of sharp chest pain that started 9 hours earlier. The current episode of pain has been ongoing for the past 3 hours. On physical examination, the pain appears to be reproducible with palpation, and the patient does not demonstrate any distress or diaphoresis. The first troponin I level is 0.03 ng/ml. The presenting electrocardiogram (Figure 1) shows sinus rhythm; one aberrantly conducted premature atrial complex; left anterior fascicular block; left ventricular hypertrophy by Cornell criteria; and subtle ST-T signs of inferior, lateral, and posterior injury. The ST-segment depression in leads V1 through V3 implies posterior ST-segment elevation of infarction. Although the ST segment is only slightly elevated in the inferior leads and in leads V5 and V6 (w0.05 mV), it has a convex morphology with a wide, hyperacute T wave, particularly evident on the aberrant complex. This morphology suggests an injury pattern, even if the ST-segment elevation is subtle. Moreover, reciprocal ST-segment depression and T-wave inversion are seen in lead aVL, further confirming that the inferior ST-T changes represent an injury pattern. Once it has been determined that ST-elevation injury is present, the next step is to identify the culprit artery. A left circumflex coronary arterial occlusion is associated with ST-