By Ken Grauer, MD

Professor Emeritus in Family Medicine, College of Medicine, University of Florida

Dr. Grauer reports no financial relationships relevant to this field of study.

The ECG in the figure below was obtained from a 60-year-old woman who presented to the ED with new-onset chest pain. The initial emergency care provider interpreted this tracing as showing complete right bundle branch block (RBBB). Do you agree? Are you concerned about anything else?

In a patient with new-onset chest pain, this tracing should be of obvious concern. The rhythm is sinus tachycardia at a rate of ~120/minute. Complete RBBB is present, as evidenced by the presence of QRS widening with predominant positivity in lead V1 and wide terminal S waves in lateral leads I and V6. But much more than just RBBB is going on in this tracing.

A deep Q wave is present in lead V1. This is not a normal accompaniment of RBBB and suggests that septal infarction probably has occurred at some point. There is marked ST segment elevation in lead V1. With simple RBBB, the opposite is expected. That is, there should be ST-T wave depression in at least leads V1 and V2 (and sometimes also in lead V3), as a natural result of the RBBB. Instead, we see definite ST elevation in both V1 and V2. Also, there is marked ST elevation in lead aVR. Virtually all other leads show marked ST segment depression, which clearly is out of proportion to what might be expected with RBBB.

An important ECG pattern to recognize is the presence of diffuse ST-T wave depression (in at least 6-7 leads) that occurs in association with ST segment elevation in lead aVR and also in V1 sometimes. In a patient with new chest discomfort, this ECG pattern often portends the presence of severe underlying coronary disease due to left-main narrowing, a high-grade proximal left anterior coronary artery lesion, and/or multi-vessel disease. Given the severity of this patient’s new-onset chest pain, the marked tachycardia, the RBBB conduction defect, and the dramatic amount of ST segment deviation (ST elevation and depression) prompt diagnostic cardiac catheterization was indicated clearly. This confirmed the presence of very severe three-vessel disease and the need for urgent revascularization.

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