ECG can suggest which territory of the 3 main cardiac vessels that COULD be compromised. ST depression in leads II, II and aVF (these are Inferior Leads)may mean some cardiac ischaemia involving the Right Coronary Artery; ST elevation in these same will spell out an acute Heart Attack for you. Go for Coronary Angiography.. now you will ''see clearly'' which vessels have what and where.

To me your dad had a heat stroke. Just rehydrate, stay in shades, stay in-doors. But at some point he will a cardiologist for the ECG changes that your doc saw. Good luck

excellent. coronary angiography will allow viewing of the coronary vessels. if any are critically blocked, they might offer several management pathways, depending on what they see. they might offer PCI ie putting a stent thru the narrowed vessels. if the vessel(s) are blocked, they might offer CABG ( the bypass you mentioned). balloon angioplasty? that's kinda old, man; but see what they offer after the angio. be aware that if the narrowing of the vessels are mild, they might offer your dad a wait-and-see approach, which is very valid. good luck to yer dad.