Subtlety and STEMI ?

Providers respond to an elderly male reporting 2 syncopal episodes earlier in the day. Upon arrival, the patient is hypotensive to 80/40. The patient is somnolent but arousable. His speech is intact. The patient responds to an infusion of isotonic crystalloid. The patient denies chest pain, abdominal pain, or vomiting.

The patient denies any medical history except orthopedic surgery several months prior. The patient takes daily aspirin and has no known allergies.

Vitals at the time of initial prehospital 12 lead:
BP: 70/P
P: 82
R: 16
Sp02: 88% on room air

Medics establish a large bore external jugular intravenous line. The patient's mental status improves as does his vital signs following a bolus of isotonic crystalloid.

BP: 110/70

P: 90
R: 16

Sp02: 95% on non re-breather

A 12 lead ECG is obtained:

12 lead ECG interpretation and discussion:A baseline sinus rhythm is present. There is minimal ST segment elevation in V1 and V2. Recall that ST segment elevation of greater than 1-2 millimeters is consistent with the diagnosis of STEMI. There is some ST depression present in the inferior leads II, III, and aVF. There are also ST segment depressions in the anterior and lateral precordial leads. The medics are concerned about acute myocardial infarction and transport to the closest cardiac interventional center. A close inspection of lead aVR reveals minimal < 0.5 mV elevation. Recall that ST elevation in lead aVR may be associated with obstructive disease of the left main coronary artery.

The presentation of syncope and hypotension is particularly ominous. Patients could be suffering from an acute myocardial infarction, aortic dissection, pulmonary embolism, or sepsis, just to name a few potentially concerning conditions. This patient's vitals warrant rapid assessment and transport. The field determination of STEMI is challenging with respect to this case but transport to a cardiac interventional center is an excellent option. Patients who are acutely hypotensive from a myocardial infarction (STEMI) are usually suffering from massive anterior wall ischemia. This ECG shows acute ischemic changes in the septal leads. Changes that occur in conjunction with a massive anterior wall MI include ST elevations in precordial leads V1-V6.

The patient's hypoxia is also alarming. This patient didn't have any known medical conditions. The acute onset of hypoxia and hypotension suggests alternative diagnoses. The hypoxia could be due to poor peripheral perfusion. However, the patient's hypoxia persisted despite adequate fluid boluses. Most patients should saturate close to 100% when on high flow oxygen.  

The patient is diagnoses with a large saddle type pulmonary embolism upon arrival at the receiving facility. Recall that risk factors for pulmonary embolism include:

-Orthopedic surgery
-Immobility
-Recent injury or venous stasis
-Birth control use
-Active cancer

As always, remember that your 12 lead ECG is a valuable tool! Have a low threshold to obtain a 12 lead ECG in patients who report syncope. The initial 12 lead findings can relay valuable information to both paramedics and emergency physicians.