In my opinion, 15-lead ECGs are not required routinely, although I would consider it for select patients.
For example, I see no value in "confirming posterior extension" of an obvious acute inferior STEMI. What difference does it make?
Likewise, in the setting of acute inferior STEMI, particularly when the RCA is suspected as the culprit artery (STE lead III > STE lead II and STD in leads I and aVL) one should presume RV infarction, particularly when the patient is bradycardic or hypotensive.
However, it's certainly reasonable to obtain a right-sided ECG (or at least lead V4R) in those circumstances.
Do I believe that you will "catch" at an acute posterior STEMI when the standard 12-lead ECG is perfectly normal? No, I do not. In fact I have offered $100.00 to anyone who can produce a normal (not just "non-diagnostic" according to conventional STEMI criteria) 12-lead ECG that shows ST-elevation in leads V7-V9 that turns out to be acute STEMI.
The caveat is that I get to use the ECGs for education, magazine articles, digital media, a book, or whatever else I want to use it for. So far I've had no takers, and I'm starting to think such an ECG does not exist.
Every single case of acute posterior STEMI I've seen shows at least a flattening of the ST-segment in the right precordial leads or an increase in the R/S ratio in lead V1 and/or V2.
Would I capture a posterior 12-lead for those patients? Absolutely! Because without an ECG showing ST-elevation there's a risk the patient may languish in a hospital bed in the emergency department and reperfusion may be delayed.
Tom