Looking Beyond STEMI

Providers respond to the report of a young patient with syncope. The patient is a young female, well conditioned, with no obvious medical history. The patient states that her resting heart rate is "usually in the 40s-50s." The patient reports mild shortness of breath which has been within the past week. The patient takes no medicines and has no known drug allergies.

Physical examination is remarkable for orthostatic hypotension.

Providers obtain a 12 lead ECG:



12 Lead ECG interpretation and discussion:
The rhythm is baseline sinus at a rate of 90 beats per minute. A first degree atrioventricular block is present. There is evidence of an incomplete (less than 0.12 seconds) right bundle branch block. Lead V1 reveals a slightly prolonged QRS duration. Close inspection of the p wave reveals increased amplitude. There are no clear cut ST-T segment changes suggestive of acute infarction.

Diagnosis is very difficult to achieve in the prehospital setting. However, astute paramedics can spot the "normal" ECG tracings from the abnormal ones. This patient's ECG and physical examination findings are extremely concerning. Hypotension in the setting of:

• Incomplete right bundle branch block
• First degree AV block
• Borderline (relative)  tachycardia

is very concerning. This ECG suggests right heart strain. Right heart strain points to the diagnosis of pulmonary embolism. Though there aren't "classic" ECG findings, the diagnosis of pulmonary embolism is supported by the relative tachycardia and shortness of breath.

The patient is transported to the receiving facility where the diagnosis of a large, saddle-type pulmonary embolism is confirmed.