Treadmill test, also known as TMT, is one of the most useful investigation modality in clinical cardiology. This is the test which can detect the blockages in coronary arteries. The test is carried out on an outpatient basis.
How Treadmill test detects blockages?
The heart is made up of muscles, and the heart is continuously pumping without a minute of rest. The heart is also having reach supply of oxygen through Coronary arteries. These coronary arteries do have reserve also. During heavy work, Coronaries can increase its blood supply by 3 to 5 times of the resting supply. So, when the demand for oxygen increases at faster heart rates, heart muscles do get enough oxygen through this normal coronaries. When coronary artery develops block, increase in the blood flow during exercise is limited. If the coronary artery is blocked by more than >70 %, then during exercise Coronary artery is not able to supply adequate oxygen to heart muscles. This causes ECG changes in proportion to the degree of blockages. Severe the block, earlier the ECG abnormality starts during a treadmill test.
Preparation before Treadmill test
preferable to have light breakfast and good hydration
Wear loose clothes, Chest electrodes will be applied during the test. These electrodes will have long wires going into a device or machine.
For hairy chest, preferable to have chest shaving done at home.
Wear your sports shoes for a comfortable walk.
If you are planning a treadmill and not accustomed to walking, go for a fast walk for a few days before going for treadmill
If you are having an increase in chest pain on walking, inform your doctor before the test. He may cancel the treadmill and advice another test.
Ask your doctor if you need to stop certain medicines.
How Treadmill test is performed?
The technician will explain to you the test
Chest area will be prepared with shaving and mild rubbing of the steriliser.
The technician will apply the gel over the chest area and then electrodes over the chest.
Demo run will be shown so that patient will understand how to walk on the treadmill.
Then we will make the patient walk on a treadmill with monitoring of his ECG, symptoms and blood pressure. Speed and slope of the treadmill are determined by patients walking capacity. Every 3 minutes speed and slop increases gradually. we target to achieve heart rate at 85 % of his target heart rate. The normal person will be able to carry out this test for 9 to 12 minutes without any chest pain or any ECG abnormality. When ECG shows abnormality at a heart rate of less than 85% of target heart rate, a test is considered abnormal and it suggests high chances of having a significant blockage in one of the major coronary arteries. Find out more about target heart rate on our blog on exercise.
I think I will not be able to walk on a treadmill
Many patients doubt that they will not be able to complete the treadmill test. Don’t worry, you are not supposed to complete the 9 min or 12 min of a treadmill. We are chasing heart rate and not the time on a treadmill. So, even if any villager women standing first time on a treadmill and because of her anxiety her heart rate increases within the first minute of a treadmill, her test is said completed.
In contrary, the fit person may continue to run for 12 minutes and his heart rate not reaching to 150, the test is considered incomplete.
Many patients do have genuine walking difficulty due to knee pain or balance issues. In this category of patients, we advise cycle based Treadmill or stress echocardiography
Risks of TMT
When advised by the doctor after proper history and ECG, Echocardiography – treadmill test is safe for the patient.
In a patient with ongoing chest pain, ECH abnormality or Echo abnormality – Doctor will not advise for the TMT.
Rare chances of having chest pain, Heart attack, giddiness during tests are there. But the patient will be on a monitor with doctor standby. Hence need not to worry.
Try to avoid getting Treadmill test on your own at a health care centre. You need to be seen by a qualified doctor and get the treadmill if he advises.
Understanding the result
The appearance of new ECH abnormality with exercise is considered abnormal TMT/positive TMT. If a patient is having symptoms during this ECG changes, reliability of the test is very high. Abnormal TMT ( we call positive TMT) requires careful attention as it means chances of having a major heart attack is very high. Your cardiologist will advice further actions looking at the overall picture.
Negative Treadmill test means you went up to your target heart rate and ECG remained normal and you didn’t have any angina.
If the patient is not able to exercise, and heart rate is not increased sufficiently, a test is considered incomplete. The patient goes for the stress echocardiography or Nuclear test for further evaluation.
If your age is more than 50, we advise you to go for TMT annually, even if you are not having any major coronary risk factors.
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