TMT provides information of blood flow of heart during stress (walking).ECG provides information about heart at resting condition only which is not sufficient to evaluate actual heart status.
During walking, our heart rates rises & heart needs more nutrition (oxygen, glucose & blood) to provide more energy. If our body provides adequate nutrition to heart, our ECG will be normal. Means heart gets adequate blood through coronary arteries. So our coronary arteries are adequately open to provide blood to heart at given stress of exercise.
If our body fails to provide adequate nutrition to the heart, it reflects on ecg & TMT test is positive for exercise induced ischemic heart disease. Our heart does not get adequate blood through coronaries which indicate some blockage of coronary arteries.
TMT has some limitations:
Some times we observe false positive as well as false negative results of TMT test. So TMT should always be correlated with clinical status, risk factors, life style of individuals & confirmed by gold standard coronary angiography (CAG).