This is the conclusion to the previous case:
This female presented to the ED with Altered Mental Status (AMS), via ambulance, as STEMI ALERT, after completing approximately 3 hours of her usual dialysis.
This was the 12 lead ECG provided by EMS…
We have a sinus rhythm with Bi-atrial Enlargement or Abnormality and Left Ventricular Hypertrophy with Secondary ST-T changes.
We can categorize ST-T changes as Primary or Secondary.
- Primary ST-T changes refer to changes due ischemia
- Secondary ST-T changes refer to non-ischemic repolarization abnormalities (i.e. LVH, Bundle Branch Blocks, ect…)
What does this mean?
This is not a STEMI, but rather ST segment elevation due to altered ventricular repolarization. A prior ECG from a previous visit was significantly similar, but we were unable to obtain a hard copy.
So remember the main reason the dialysis center called EMS? AMS. The patient was found to be hypoglycemic and was treated with 25 g of Dextrose 50% with improved mental status and GCS.
The following 12 lead ECG was obtained:
Both computerized ECG interpretation recognized Secondary ST-T changes, as well as Atrial abnormality, with no STEMI recognized. Although the computerized interpretation is accurate in most case, our ability to interpret ECGs is one of the most important skills as healthcare providers and clinicians, which is why we will break down our findings in this case.
What do we see?
- Sinus rhythm, regular with PRI within normal range
- Physiologic leftward axis
- Prolonged QTc
- Biatrial Enlargement or Abnormality: (as discussed before, many clinicians have adopted the term abnormality over enlargement due to the possibility of atrial dilation or hypertrophy, not confirmed by ECG)
- Right Atrial Enlargement/Abnormality (P Pulmonale): P wave > 2.5 mm in lead II
This is usually present in cases of chronic Pulmonary HTN and increased Right Ventricular (RV) workload
Click HERE for further on Pulmonary pressures and ECG changes
- Left Atrial Enlargement/Abnormality: in this case, deep P wave > 40ms between downslope and upslope in V1
This is usually present in cases of Mitral or Aortic Valve stenosis, chronic systemic HTN and increased Left Ventricular (LV) workload
- LV Strain pattern: Slight downsloped ST segment depression with asymmetric T wave inversion, suggesting increased LV workload (secondary ST-T change, not ischemia)
- Left Ventricular Hypertrophy (LVH): Many criterias exist to determine LVH, but we will focus on some of the most commonly used:
Sokolow Lyon Criteria
- S wave in V1 + R wave in V5 or V6 > 35mm
- S wave in V3 + R wave in aVL > 28 mm in men
Other common criterias included:
- R wave in aVL > 11 mm
- R wave in Lead I + S wave in lead III > 20 mm
- R wave in V4-6 > 25 mm
Notice how the highest ST segment elevation is present in the leads with the deepest S waves, V1-3. This means that the elevation is proportional to the depth of the S wave. In simple terms:
The deeper the S wave, the higher the ST segment. The taller the R wave, the deeper the St segment.
This is why LVH is known to be an Anterior STEMI mimic
A very useful means to help differentiate between LVH and LVH with MI, is looking at the QRS/T ANGLE. This is the difference between the QRS and T wave axis, and that difference, when >100, is a good indicator of LVH with strain pattern, rather than LVH with MI.
Although the ST segments in V2-3 are not the common concaved elevation seen in these precordial leads, there are no other signs of MI, with normal R wave progression and no changes over time.
The presence of Atrial abnormality and history of HTN supports the diagnosis of LVH, although, the confirmation of hypertrophy is best obtained with Echocardiogram, revealing the true LV muscle mass and index.
Troponin I was .08 ng/dL during this event, while the last two ED visits, one month apart, were .16 ng/dL and .21 ng/dL, secondary to renal failure and HTN. No occluded arteries were found during previous angiogram with no ECG changes. Serum Potassium of 4.7 mEq/L. The patient was admitted for further observation with no cardiac complications, and overall improvement.