By Ken Grauer, MD, Professor, Assistant Director, Family Practice Residency Program, University of Florida
Dr. Grauer reports no financial relationships to this field of study.
Figure. 12-lead ECG obtained from a 75-year-old woman with new-onset shortness of breath.
Clinical Scenario: The 12-lead ECG in the Figure was obtained from a 75-year-old woman who presented with shortness of breath but no chest pain. There is complete RBBB (right bundle branch block). What else do you see? In view of this clinical presentation, what should you be concerned about?
Interpretation/Answer: Although P wave amplitude is small, regular upright P waves do appear to precede each QRS complex with a normal PR interval in lead II, as well as being present in several other leads. Thus, there is normal sinus rhythm. As noted above, QRS widening is explained by the presence of complete RBBB. Regarding chamber enlargement, there may be ECG evidence of LAE (left atrial enlargement), as seen from P wave notching in lead II (albeit the small size of overall P wave amplitude). However, the most remarkable finding in this example of complete RBBB is the presence of flat ST segment depression in leads V4 through V6. There is also ST segment depression in lead V3, and to a lesser extent in leads V2 and the inferior leads.
The finding of flat ST segment depression in multiple leads of a 12–lead tracing is worrisome, especially when it occurs in association with a symptom complex that could be acute, such as the case here. At least one third of all myocardial infarctions occur in the absence of chest pain. About half of these are completely “silent” (ie, no symptoms at all), whereas the other half have non-chest pain symptoms. Of these, shortness of breath is by far the most common non-chest pain symptom associated with “silent” myocardial infarction. Recent acute myocardial infarction should be suspected in this case given the history (older adult with new-onset shortness of breath), and ECG findings of RBBB of uncertain age, diffuse deep ST depression in multiple leads, and somewhat widened lateral q waves that may be more than just normal septal q waves. Positive serum troponins confirmed our clinical suspicion.
The 12-lead ECG in the Figure was obtained from a 75-year-old woman who presented with shortness of breath but no chest pain. There is complete RBBB (right bundle branch block). What else do you see? In view of this clinical presentation, what should you be concerned about?
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