Percutaneous Transluminal Coronary Angioplasty Improves Oxygen Uptake Kinetics During the Onset of Exercise in Patients With Coronary Artery Disease

摘要

Study objectives: Although percutaneous transluminal coronary angioplasty (PTCA) is known tonhave beneficial effects on exercise capacity, its effects on the cardiovascular response during thenonset of exercise have not been clarified. The present study was undertaken to determine theneffects of PTCA on the kinetics of oxygen uptake (V ˙O2) during constant-work-rate exercise innpatients with coronary artery disease, as well as on their indexes of maximal work capacity.nMethods: Seventeen patients with coronary artery disease who received successful PTCAsnperformed a 50-W constant-work-rate exercise test for 6 min and a symptom-limited incrementalnexercise test both before and 4 months after the PTCA procedure. V ˙O2 was calculated fromnbreath-by-breath analysis of respired gases. The time constant of V ˙O2 kinetics during the onset ofn50-W exercise was determined by fitting a single exponential function to the V ˙O2 response.nResults: In 14 patients without coronary restenosis, the time constant of V ˙O2 kinetics wasnsignificantly shortened from (mean 6 SD) 57.4 6 12.6 before PTCA to 48.2 6 9.5 s after PTCAn(p 5 0.0035), indicating improved kinetics of the V ˙O2 response. In these subjects, the peak V ˙O2nobtained during maximal exercise testing also increased from 23.1 6 3.5 to 26.5 6 3.2 mL/minkg, respectively (p 5 0.0005). However, there was no improvement in these indexes in thenpatients who had restenosis after undergoing PTCA (n 5 3).nConclusion: Indexes of cardiopulmonary exercise testing, which reflect an efficiency of oxygennflow to the exercising muscle, can be used as an objective, noninvasive, and cost-effective guidenfor understanding which patients will not have coronary restenosis following PTCA.