The Asymptomatic Cardiac Ischemia Pilot (ACIP) and modified ACIP treadmill exercise protocols were developed to test patients with coronary artery disease and to linearly increase work load between stages. The physiologic changes that occurred with ACIP and modified ACIP were compared to those with the Bruce and Cornell protocols in 28 normal subjects and 16 men with coronary artery disease. The exercise protocols were randomly assigned over 2 days, and gas exchange data were obtained continuously with each test. In normal subjects, the peak heart rate, systolic blood pressure, peak oxygen consumption rate (VO2) and minute ventilation were similar for the 4 protocols tested, with exercise time shortest for the Bruce protocol in comparison with the ACIP, modified ACIP and Cornell protocols (10.2 ± 3.1 vs 13.4 ± 4.9, 13.9 ± 4.5, and 15.0 ± 4.2 minutes, respectively; p < 0.001). The difference between predicted and observed VO2 was smallest for the ACIP protocol (37.0 ± 11.0 vs 35.8 ± 13.5 ml/kg/min) and greatest for the Brace protocol (41.1 ± 11.8 vs 36.7 ± 15.0 ml/ kg/min) in normal subjects, as well as in patients with coronary artery disease (ACIP protocol 26.9 ± 7.1 vs 22.5 ± 6.7, and Brace protocol 29.1 ± 7 vs 22.6 ± 5.7 ml/kg/min, respectively). The ratio of VO2 to work rate, expressed as a slope, was similar in normal subjects for the 4 protocols tested. However, in patients with coronary artery disease, the slope was 0.84 and 0.83 for the ACIP and modified ACIP protocols, respectively, versus 0.61 and 0.71 for the Brace and Cornell protocols, respectively. Ischemic ST-segment depression was detected in 93.8, 87.5 and 100% of patients with coronary artery disease using the ACIP, modified ACIP and Brace protocols, respectively, and in 62.5% using the Cornell protocol. In conclusion, the ACIP and modified ACIP treadmill protocols result in a steady and moderate increase in work load between stages, resulting in linear increments in heart rate and VO2, with similar peak expired gas parameters to those of the Bruce protocol.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine