Background: The effect of percutaneous transluminal coronary angioplasty (PTCA) on physiologic measurements has previously been shown, but the relation between physiologic response and degree of change in coronary luminal diameter is not known. We studied the relation between exercise capacity and minimal luminal diameter before and after PTCA. We also explored the usefulness of measurement of attenuation in exercise capacity after PTCA to predict the likelihood of restenosis.
Methods: Bicycle exercise testing was performed 2 weeks before and 2 and 20 weeks after PTCA in 395 consecutively enrolled patients. Angiograms obtained before and after PTCA and 20 weeks afterward were analyzed by quantitative coronary angiography. Restenosis was defined as both angiographic (>/=50% diameter stenosis at follow-up angiography) and clinical (target-vessel revascularization), after successful PTCA. Exercise capacity was defined as the cumulative work performed divided by body weight (watt x minutes x kilograms(-1)).
Results: Exercise capacity increased 43% (P <.0001) from before PTCA to 2 weeks after PTCA (early increase) and decreased 4% (P =.01) from 2 to 20 weeks after PTCA (late decrease). The gain in minimal luminal diameter (Minimal luminal diameter after - Minimal luminal diameter before) was 0.92 +/- 0.46 mm. The loss in minimal luminal diameter (Minimal luminal diameter after PTCA - Minimal luminal diameter at follow-up examination) was 0.27 +/- 0.42 mm. Exercise capacity and minimal luminal diameter measured before PTCA were positively correlated (coefficient 3.3; R = 0.12; P =.01). Gain in minimal luminal diameter correlated with the early increase in exercise capacity (coefficient -3.8; R = 0.23; P <.0001). Loss in minimal luminal diameter correlated with the late decrease in exercise capacity (coefficient 3.3; R = 0.20; P <.0001). Multivariate logistic regression analysis revealed that the late decrease in exercise capacity was independently predictive of both angiographically (odds ratio 1.13; P <.0001) and clinically (odds ratio 1.12; P <.0001) defined restenosis.
Conclusions: The results demonstrated a linear relation between the severity of coronary stenosis and exercise capacity measured before PTCA. The degree of coronary luminal enlargement achieved with angioplasty and the luminal reduction that occurred between PTCA and follow-up evaluation correlated with increases and decreases in exercise capacity. Attenuation in exercise capacity was found to be a strong predictor of restenosis.