Relationship between functional exercise capacity and functional stenosis in patients with stable angina and intermediate coronary stenosis.

Background: Some stable angina patients with significant coronar function have low exercise capacity, whereas some have high exercise capacity. The aim of the present study was to determine whether coronary pressure-derived fractional flow reserve (FFRmyo), a functional index of coronary stenosis, is a better indicator of exercise capacity than angiographic stenosis. Methods and Results: The 15 male (65.8 +/- 8.9 years old) subjects with stable angina and 75% angiographic stenosis underwent a cardiopulmonary exercise test (CPX), and peak oxygen uptake (Peak(V) over dot O-2) and oxygen uptake at anaerobic threshold (AT) were measured. The relationship between FFRmyo and CPX values was assessed. The left anterior descending artery was affected in 8 patients, the left circumflex artery in 5, and the right coronary artery in 2. Percent diameter stenosis (%DS) was 61.7 +/- 9.1% by quantitative coronary angiography. Mean FFRmyo, Peak(V) over dot O-2, and AT was 0.84 +/- 0.66, 17.1 +/- 3.2 ml.kg(-1).min(-1), and 11.1 +/- 2.0 ml.kg(-1).min(-1), respectively. There was no significant correlation between %DS and FFRmyo, Peak(V) over dot O-2, or AT (r=0.12, -0.051, and -0.013, respectively; P=NS), but FFRmyo had a significant positive correlation with Peak(V) over dot O-2 and AT (r=0.534 and 0.542, respectively; P<0.05). Conclusions: Exercise capacity reflects functional stenosis in stable angina patients. (Circ J 2009; 73: 2308-2314)