Effect of enhanced external counterpulsation on resting oxygen uptake in patients having previous coronary revascularization and in healthy volunteers.

This study analyzed the acute effects of enhanced external counterpulsation (EECP) on oxygen uptake (VO2) at rest in adults with symptomatic coronary artery disease (CAD) compared with healthy volunteers. EECP therapy increases exercise tolerance in patients with refractory angina pectoris. This may be attributed, at least in part, to a training effect, but measurement of VO2 during an EECP treatment session has not been previously reported. We measured VO2 continuously in 20 adults during a single treatment session of EECP, including 10 subjects with previous coronary revascularization who were referred for EECP therapy for refractory angina, and 10 healthy, sedentary volunteers. VO2 was measured for 10 minutes before EECP, during a 30-minute EECP treatment session, and for 10 minutes after cessation of EECP treatment. Patients with CAD were older (65.9 +/- 12 vs 38.5 +/- 7 years, p = 0.002) and had a higher body mass index (32.0 +/- 10.0 vs 25.5 +/- 3.0 kg/m2, p = 0.027) and percent body fat (37 +/- 7% vs 21+/-9%, p = 0.006). VO2 at rest, although slightly lower in the CAD group, was not significantly different (2.75 +/- 0.54 vs 3.19 +/- 0.51 ml/kg/min, p = 0.09). The 2 groups demonstrated a small, sustained increase in VO2 during EECP treatment (CAD +0.66 +/- 0.56 ml/kg/min, p < 0.005; healthy +0.72 +/- 0.40 ml/kg/min, p < 0.001; CAD vs healthy, p = 0.13), which returned to baseline levels during recovery. In conclusion, VO2 at rest is increased to the same degree during an EECP treatment session in healthy subjects and symptomatic patients with CAD. This effect may contribute to the increased exercise tolerance of patients with refractory angina after receiving EECP therapy.