EFFECTS OF CARDIAC ALLOGRAFT VASCULOPATHY ON MYOCARDIAL BLOOD-FLOW, VASODILATORY CAPACITY, AND CORONARY VASOMOTION

Background Coronary vasculopathy is the third leading cause of death 1 year after cardiac allograft transplantation. This study was designed to assess the hemodynamic effects of transplant vasculopathy on myoca rdial blood Bow and vasomotion. Methods and Results Thirty-two patient s were studied 1 to 2 years after cardiac transplantation by use of po sitron emission tomography (n=32), intravascular ultrasound (n=26), co ronary angiography (n=32), and endomyocardial biopsy (n=32). Twenty he althy individuals served as control subjects. Quantitative intravascul ar ultrasound was used to compute coronary lumen area, intimal thickne ss, and intimal index [Intima Area/(Intima+Lumen Area)]. Myocardial bl ood flow was quantified with the use of N-13-ammonia/positron emission tomography. Mean myocardial blood flow was higher in the transplant p atients than in control subjects (0.94+/-0.26 versus 0.68+/-0.16 mL . min(-1) . g(-1); P<.0005). Cold increased myocardial blood flow to 0.7 9+/-0.18 mL . min(-1) . g(-1) in control subjects but not in patients (0.98+/-0.36 mL . g(-1) . min(-1)). Hyperemic myocardial blood flow wa s lower in patients than in control subjects (1.69+/-0.78 versus 2.30/-0.32 mL . min(-1) . g(-1); P<.05) and was inversely related to maxim al intimal thickness and intimal index (all P<.05). The myocardial flo w reserve was reduced in patients (1.82+/-0.55 versus 3.45+/-1.03; P<. 0001). Conclusions The degree of intimal thickening is correlated with abnormalities in coronary function in patients with diffuse cardiac a llograft vasculopathy. The reduction in vasodilatory capacity and the abnormal blood Bow response to cold suggest abnormalities in endotheli um-dependent and -independent coronary vasodilation in transplant reci pients.