Stress Testing (TMT – Treadmill stress test)

• It is the best test for angina.
• 12 – lead ECG is recorded before, during, and after exercise on a bicycle or treadmill ergom­eter.
• Patient’s ECG, arm blood pressure, heart rate, symptoms are monitored and the work load is gradually increased.
• Exercise ECG testing is a preferred component of stress testing in most patients.
• Stress testing is an important modality for the evaluation of patients with known or suspected coronary heart disease (CHD),
• The emphasis will be on stable patients with known CHD
• The test is stopped if patients gets chest dis­comfort, dyspnoea, fatigue, dizziness and ST-T changes (ST depression >2 mm), systolic blood pressure falls more than 10 mmHg, patient gets ventricular tachyarrhythmias.
• The percentage of irreversibly scarred myocardium
• Compare symptoms, especially chest discomfort or pain with ECG changes.
• The amount and distribution of viable but jeopardized left ventricular myocardium

Stress test / Treadmill stress test positive

• The degree of ischemia can be graded semiquantitatively by each of these methods.
• If ST depression >0.1 mv below baseline for more fhan 0.08 seconds or 2 small squares.
• Exercise or pharmacologic stress (mostly using dobutamine) echocardiography;
• ownsloping ST is significant

The measure of induced ischemia —

• Abnormally low peak systolic blood pressure (<130 mmHg) or a fall in systolic blood pressure below baseline during exercise
• Poor exercise capacity (<5 METs) (show figure 1)
• Exercise-induced angina, particularly at a low workload
• Chronotropic incompetence
• Evidence of ischemia may be assessed in several ways,
• T wave changes, conduction abnormalities, veD­tricular and atrial arrhythmias ma not sig.o.jfy CAD.
• Target heart rate -i.e. 85% maximum heart rcrre fo r ag e a nd sex, if Qot achi eve_d, testLs non-di~gnostic.
• ensitivity of TMT is only 75% ( Treadmill stress test)
• Complications and risks ofTMT (Treadmill stress test) One death can occur per 10,000 cases so equipments for resuscitation must be present.

Contraindications :

• Acute MI (within 4-5 days)
• Rest angina <48 hrs Unstable rhythm
• Severe aortic stenosis Myocarditis
• Heart failure
• Acute infective endocarditis
• Severe IHD is signified by .’
• >0.2 mv ST segment depression at low ~orkload (before stage II).
• ST segment depression> 5 minutes after termination of exercise.
• adionuclide studies

• This shows the m ocardium and hence infarcted ar­eas of the myocardium i.e. its viability can be seen.

Stress Myocardial Perfusion Imaging:

• IV Thal­lium 201 or Technetium 99 m is given and then imag­ing is done immediately and after 4 hours to detect regions of infarction.
• With thallium, infarcted areas do not take up the dye (cold spots). With technetium, infarcted areas take up the dye (hot spots).

The Duke treadmill score uses three exercise parameters:

• Duke prognostic treadmill score = Exercise time (minutes based on the Bruce protocol) – (5  x  maximum ST segment deviation in mm)  –  (4  x  exercise angina [0=none, 1=nonlimiting, and 2=exercise limiting])
• Patients are classified as low, moderate, or high risk according to the score:
• Low-risk — score ≥ +5
• Moderate-risk — score from -10 to +4
• High-risk — score ≤ -11
• 16 percent had single vessel disease, and 9 percent had three vessel or left main disease; five-year survival was above 97 percent.
• Among the 9 percent of patients categorized as high-risk, 74 percent had three vessel or left main disease and five-year survival was 65 percent.
• Among the 36 percent of patients categorized as low-risk, 60 percent had no coronary stenosis ≥ 75 percent,