Post show many people stop diuretics, they have high potassium and low sodium (if they do not sodium load), also hormone aldosterone kicks in if water was stopped for more than 12hrs - leading to edema after water is re-introduced in larger amounts. Now after the show many people stops K intake, drink water excessively because of thirst and add that junk foods have excessively high leveks of NaCl. So off course this may lead to complications with heart later - like 12-24hrs after....
Smart way is keep some K in, add magnesium as it is a mineral ballancing the two, add sodium SLOW and also increase water intake SLOWLY. I drink post show but building up my regular intake over 2-3 days to avoid edema - it works. Edema may increase blood pressure. But to me the main culprit is the sudden elevation of NaCl with steep drop in K in hours following show. So before show Na dropping, K rising, after the opposite happen...all this in very short period of time...
Also European protocols were always harsher than US. Many avoid water for 48 hours, many even adds more K while having K sparring diuretics etc. Thats why I stopped doing it.