1. Performing TWA Tests: Tips for Reducing Indeterminate Test Results (Dan Bloomfield MD) Importance of gradual increase in heart rate between 90 - 110 bpm Aim for heart rates of 120 bpm Maximal effort needed for patient with maximal heart rates < 105 bpm Role of immediate re-testing Train physicians and staff to interpret tests

2. Importance of Gradual Increase in Heart Rate from 90 - 110 bpm Interpretation of TWA often depends heavily on whether alternans is present between heart rates of 90 - 110 Goals during exercise testing: – low noise levels – gradual increase in heart rate from 90 - 110 over 2 - 4 minutes

3. Tips to Achieve Gradual Increase in Heart Rate from 90 - 110 Press ‘Start Treadmill’ key prior to pressing “Start Exercise” While in the standing stage, have the patient practice walking on the treadmill for 15-30 seconds at its minimum speed and at a 0% grade Ensure that the patient is calm and comfortable walking on the treadmill before starting exercise Once the patient is comfortable, press the “Start Exercise” key.

4. Tips to Achieve Gradual Increase in Heart Rate from 90 - 110 When running a treadmill stress test with alternans, it is important that the patient’s heart rate does not increase too rapidly from 90 - 110 BPM Patients who have limitations in exercise tolerance are ill not fit. – Treadmill testing: use a Naughton or Modified Bruce protocol – Bicycle Ergometer testing: use a ramp protocol (or manually increase worload

5. Tips to Achieve Gradual Increase in Heart Rate from 90 - 110 If the increase in the patient’s heart rate from 90- 110 BPM is too rapid for accurate alternans determination, a message will be displayed. If this message is displayed, it is advisable to stop the test, allow the patient’s heart rate to decrease to below 100 BPM, and then restart the test.

6. Target Heart Rate of 120 bpm Goal is to have a test with a 3-4 minutes of alternans over range of heart rates – allows interpretation of alternans in presence of artifacts – appreciate relationship between the increasing in heart rate and the increase in alternans magnitude Alternans starting at 104 bpm may be hard to interpret if test is stopped after 1 minute at 105 bpm

7. Maximal effort required for patient with maximal heart rates < 105 bpm Under current rules, patients with MaxHR < 105 bpm cannot be negative New rules ( B Rules) evaluated in The Lancet Paper suggest that patients without alternans and with MaxHR 80 bpm are at low risk if the test was a maximal test and (MaxHR-MaxNegHR) < 5bpm Treadmill exercise more likely to result in HR > 105 than bicycle exercise

8. Role of Repeat Testing “Exercise Protocol Failure” – Rapid rise in heart rate Some T wave alternans test results are ambiguous, repeat testing may be helpful Immediate repeat testing reduces indeterminate test results by 50%

9. Value in Interpreting Numerous T Wave Alternans Test Interpreting tests provides valuable feedback about the exercise protocol and the importance of rate of change of heart rate during testing Train staff to interpret tests – CD Training Course suitable for physicians, nurses, technicians – Course includes > 150 tracings to interpret – Collect and re-interpret your own tracings