What do flat t waves mean on an ekg?

Low Potassium. Flat t waves can indicate that you are low in potassium (k) or that you are experiencing some ischemia (lack of oxygen) to your heart. Was this a routine ekg? Or was it a stress test? Depending on the answer, your doctor may want some more tests to evaluate blood flow to the heart.
Depends. Without symptoms flattening of the t waves would likely be considered a nonspecific finding. This may be seen in normal healthy people but can also be caused a number of conditions and even drugs. In a patient with heart disease or cardiac symtoms, this finding may be a subtle indication of ischemia. This means the heart is not getting enough oxygen. See a cardiologist for more details.