Value of TMT

Exercise testing• It is better known as Exercise electrocardiographic testing.

• It most fundamental and widely used tests for the evaluation of patients with cardiovascular disease (CVD).

• Initially developed to detect the presence of myocardial ischemia secondary to coronary artery disease (CAD)

• Now recognized for its power in predicting prognosis.

Other uses• Valvular heart disease• Congenital heart disease • Genetic cardiovascular conditions.• Arrhythmias.• Peripheral arterial disease (PAD).

Physiology of exercise testingTOTAL BODY OXYGEN UPTAKE:• Energy requirements at rest and for any given amount of physical activity

(work rate) can be estimated from measurements of total-body oxygen uptake (V O2).

• VO2 is equal to the product of cardiac output and oxygen extraction at the periphery.

• VO2 is easily expressed in multiples of resting oxygen requirements (metabolic equivalents [METs].

• 1 MET being resting energy expenditure and defined as approximately 3.5 mL oxygen/kg body weight/min.

• Therefore, 5-MET activity requires five times the energy expenditure at rest.

• VO2max is the peak oxygen uptake achieved during performance of the highest level of dynamic exercise involving large muscle groups.

Patients assessment:

Contraindications:

Exercise Test Modality and Protocols• Patient’s estimated functional capacity based on age, estimated

physical fitness from the patient’s history, and underlying disease.

• Treadmill and stationary cycle ergometers.

• use stepped or continuous ramp protocols

• Work rate increments (stages) during stepped protocols can vary from 1 to 2.5 METs.

• Ramp protocols are designed with stages that are no longer than 1 minute and for the patient to attain peak effort within 8 to 12 minutes.

• Ramp protocols must be individualized and selected to accommodate the patient’s estimated exercise capacity.

• Submaximal tests are used in patients early after myocardial infarction before discharge from the hospital because they can provide prognostic information to guide management.

• They are useful in the evaluation of a patient’s ability to engage in daily activities after discharge and in addition serve as a baseline for cardiac rehabilitative exercise therapy

TMT• Treadmill testing provides a more common form of physiologic stress

(i.e., walking) in which

• In this subjects are more likely to attain a higher oxygen uptake and peak heart rate than during stationary cycling

• The most frequently used stepped treadmill protocols are the Bruce protocol.

• Patients should be encouraged to walk freely and use the handrails for balance only when necessary.

• This will prevent overestimation of exercise capacity and an inaccurate heart rate– and blood pressure–to-workload relationship.

• Exercise capacity (peak METs) can be reasonably estimated for treadmill exercise

Stationary Cycle• Cycle ergometer is smaller, quieter, and less expensive than a

treadmill.

• Quality electrocardiographic recordings and blood pressure measurements are easier to obtain.

• Involves cycling at a given pace against an external force and is generally independent of the patient’s body weight, which is supported by the seat.

Cardiopulmonary Exercise Testing.• It uses ventilatory gas exchange analysis during exercise to provide a

more reliable and reproducible measure of VO2.

• Peak VO2 is the most accurate measure of exercise capacity and is a useful reflection of overall cardiopulmonary health.

Exercise test supervision • Patients be screened before exercise testing to assess their risk for an

exercise-related adverse event.

• Personal supervision requires a physician’s presence in the room only if the screening has labelled high risk for TMT.

• It is supervised by nonphysician staff members but physician should be available to attend emergency.

Risk of exercise testing• It has an increased risk for an adverse cardiovascular event.

• Recent myocardial infarction, reduced left ventricular systolic function, exertion-induced myocardial ischemia, and serious ventricular arrhythmias are at highest risk.

• Safety of exercise testing is well documented and the overall risk for adverse events is quite low.

• Major complications (including myocardial infarction and other events requiring hospitalization) was less than 1 to as high as 5 per 10,000 tests.

• The rate of death was less than 0.5 per 10,000 tests.

Monitoring during the test:

Indication for terminating the test

Diagnostic utility:• Pre test probability• Prognostic utilization • Acute coronary syndrome• Post MI risk stratification• Role in chest pain unit

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