Did an ecg and got high t waves, what are the causes for that?

Normal: It can be perfectly normal. The classic pathological cause is elevated potassium but this would generally only occur in renal failure or overdose of a supplement. In people with acute chest pain, the very earliest sign of a heart attack can be a brief and temporary "hyperacute" peaking of the t wave. For most, though, it's a normal finding.

ECG : There are t waves and then t waves. They can be prominent and have little meaning, very high t waves are usually caused by elevated potassium.