Percutaneous transluminal coronary angioplasty improves oxygen uptake kinetics during the onset of exercise in patients with coronary artery disease

Study objectives: Although percutaneous transluminal coronary angioplasty (PTCA) is known to have beneficial effects on exercise capacity, its effects on the cardiovascular response during the onset of exercise have not been clarified, The present study was undertaken to determine the effects of PTCA on the kinetics of oxygen uptake ((V) over dot(O2)) during constant-work-rate exercise in patients with coronary artery disease, as well as on their indexes of maximal work capacity. Methods: Seventeen patients with coronary artery disease who received successful PTCAs performed a 50-W constant-work-rate exercise test for 6 min and a symptom-limited incremental exercise test both before and 4 months after the PTCA procedure. (V) over dot(O2) was calculated from breath-by-breath analysis of respired gases. The time constant of (V) over dot(O2) kinetics during the onset of 50-W exercise was determined by fitting a single exponential function to the (V) over dot(O2) response. Results: In 14 patients without coronary restenosis, the time constant of (V) over dot(O2) kinetics was significantly shortened from (mean +/- SD) 57.4 +/- 12.6 before PTCA to 48.2 +/- 9.5 s after PTCA (p = 0.0035), indicating improved kinetics of the (V) over dot(O2) response. In these subjects, the peak (V) over dot(O2), obtained during maximal exercise testing also increased from 23.1 +/- 3.5 to 26.5 +/- 3.2 mL/min/kg, respectively (p = 0.0005), However, there was no improvement in these indexes in the patients who had restenosis after undergoing PTCA (n = 3). Conclusion: Indexes of cardiopulmonary exercise testing, which reflect an efficiency of oxygen flow to the exercising muscle, can be used as an objective, noninvasive, and cost-effective guide for understanding which patients will not have coronary restenosis following PTCA.