Exercise Treadmill Testing

A modification of the modified Naughton protocol was used for exercise testing. The primary endpoint was total time that the subject performed exercise (symptom-limited). Treadmill speed was 1.5 mph for stage 1; all subsequent stages had a speed of 2.5 mph. Stage duration was 1 min for stages 1 and 2; all other stages lasted 2 min. Grade was 0% for stages 1 and 2; grade increased by 2.5% every 2 min starting at the end of stage 2. Heart rate, blood pressure, and ECG were recorded during each stage and patient symptoms were monitored. Subjects were asked to discontinue β-adrenergic receptor antagonists (β-blockers) for one day prior to testing.