This is the conclusion to 41 year old female: chest pain.
I think we would all agree the patient presentation is suspicious for ACS. Let's review the first 12 Lead:
The rhythm is sinus tach. There is about 1mm of ST elevation in V1, and depending on where you spot your J point, little to no elevation in leads V2, V3. There is about 1mm of ST depression in leads I, II, and V6. Lead III also has a Q wave and an inverted T wave. However, both a Q wave and an inverted T wave in lead III may be normal. One could definitely argue this is a suspicious looking 12 Lead, but I'm not sure if any of us would activate the cath lab based on this ECG alone. If serial ECG's are not done, the cath lab is not activated, and likely nothing will be discovered to change that.
But, you are all well aware of the importance of serial ECG's, and so was the Medic on this call. So let's take a look at the second 12 Lead, taken only 7 minutes later:
There are obvious dynamic changes here. For starters, there are now hyperacute T waves that tower over the QRS in leads V2 and V3, and are much larger than they were in V4. They are localized to leads V2-V4 and "point" to the area of infarct. The ST elevation in leads V1 and V2 is now 3mm, and in V3 is 3-4 mm. The ST depression in leads I, II, and V6 have deepened slightly. The T wave inversion in lead III has deepened, and there is now measurable ST depression in aVF. Also, there is subtle loss of the R wave in leads V2-V3. On its own, this ECG is probably diagnostic of STEMI, but with the dynamic changes compared to the first one, it is virtually assured.
In the third 12 Lead:
The hyperacute T waves are not as towering as they were…the ST elevation in V1-V3 are now 1-2mm, and the ST depression has greatly resolved. The inverted T wave in lead III is now mostly upright. These changes are likely the result of the treatments given by the Medic, perhaps some reperfusion of the culprit artery.
To illustrate how dynamic these changes were over the course of the three ECG's, have a look at leads V1-V3 side by side:
At the cath lab, the patient was found to have an occlusion of the LAD, for which she was stented.
Some key points to take away:
- The importance of serial ECG's can not be overstated.
- Subtle changes,such as straightening of the ST segment or subtle enlargement of the T wave may be the first change on the ECG.
- Hyperacute T waves are localized, and "point" to the area of infarct.
- ST deviations may normalize after treatments such as ASA, NTG… Failure to do serial ECG's may delay patient care if these deviations are missed. For additional information on this point, see this excellent post on Dr. Smith's ECG Blog.