Treadmill test (TMT)

Treadmill test (TMT) or exercise stress test is one of the commonest forms of stress tests used to induce provokable myocardial ischemia for diagnostic evaluation of coronary artery disease. Other forms of stress test are dobutamine stress echocardiography and adenosine stress test. In treadmill exercise test, the subject walks on a treadmill as per the protocol of the test. One of the commonest protocol used is known as Bruce protocol. Every stage of Bruce protocol consists of three minutes. The starting speed is 1.7 miles per hour (mph) and the gradient is 10%. 0.7-08 mph increment in speed and 2% increment in gradient is given for each consecutive stage. Usual Bruce protocol has upto 7 stages, but most often when it is done in a post myocardial infarction patient, upto 10 minutes of exercise is taken as sufficient.

The heart rate and blood pressure are monitored continuously along with 12 lead ECG with computerised ST and arrhythmia detection algorithms. Test is stopped if the subject develops limiting angina, syncope, breathlessness, fatigue or when the target heart rate is achieved.

Significant ST depression of 3 or more millimeters is also an indication for termination. Occasionally the test has to be terminated because of serious cardiac arrhythmia. A defibrillator and qualified personal and equipment for resuscitation should be available during the test.