Here’s the conclusion to 81 year old male CC: Palpitations.
Let’s take another look at the 12-lead ECG.
Some of you expressed concerns about the possibility of the ECG abnormality we sometimes refer to as left ventricular aneurysm (persistent ST-elevation after previous MI).
To put it another way, some of you think this STEMI looks “old”.
Stephen Smith, M.D. of Dr. Smith’s ECG Blog has a decision rule to help distinguish LVA from acute anterior STEMI by looking at the T/QRS ratio in leads V1-V4. T/QRS ratio best distinguishes ventricular aneurysm from anterior myocardial infarction. Am J of Emerg Med 2005 May; 23(3):279-287.
A high T/QRS ratio indicates acute STEMI. A low T/QRS ratio indicates LVA.
To come up with the T/QRS ratio you measure the amplitude of the T wave and divide by the depth of the S-wave.
If there is one lead in V1-V4 with a T/QRS ratio > 0.36, then STEMI is likely.
Or, if the sum of the T-waves in V1-V4 divided by the sum of the S-waves in V1-V4 > 0.22, then STEMI is likely.
Let’s look at the current case.
Lead V4 shows a T/QRS ratio of 0.38 which is suggestive of acute STEMI.
Let’s try the more complicated calculation (TV1+TV2+TV3+TV4 divided by SV1+SV2+SV3+SV4).
1+1.5+6+5 = 13.5
11+13+18+13 = 55
13.5/55 = 0.24 (T/QRS ratio)
Remember, the cut-off is 0.22 so this is very close but favors acute STEMI.
Finally, let’s consider another of Dr. Smith’s ECG interpretation tips: the rule of proportionality.
Lead V5 in this case shows a little bit of ST-elevation but the QRS complex is small. Let’s consider the ST/QRS ratio in this lead.
Here we use PowerPoint to “stretch” the QRS complex while preserving the ST/QRS ratio.
Looks pretty impressive to me!
Another finding that supports acute STEMI is the well formed R-waves in leads V3 and V4.
Typically LVA shows QS-complexes in leads V1-V4.
Diagnosis: Acute anterior STEMI (confirmed with angiography)