Predictors of reduced coronary flow reserve in heart transplant recipientswithout angiographically significant coronary artery disease

Background. Determination of coronary flow reserve (CFR) is increasingly us ed to assess the functional significance of cardiac allograft vasculopathy, Although the relation between CFR and angiographically defined vasculopath y has been studied extensively, little is known about other factors determi ning CFR in heart transplant recipients without significant lesions by coro nary angiography. Methods. Sixty consecutive patients were studied 0.5 to 148 months after he art transplantation with intracoronary Doppler and intravascular ultrasound , An endothelium-independent CFR less than or equal to 2.5 was defined as a bnormal, Stepwise logistic regression analysis was used to identify factors (demographic data of donor and recipient, lipid profile, epicardial vessel morphology by intravascular ultrasound, left ventricular hypertrophy, acut e rejection episodes, and hemodynamics) potentially associated with a reduc ed CFR. Results. Only the presence of left ventricular hypertrophy (48% vs, 14%, P= 0.007 and P=0.023, bivariate and multivariate analysis, respectively) and h igher donor ages (41+/-12 vs, 29+/-11 years, P=0.002 and P=0.013, bivariate and multivariate analysis, respectively) showed an independent association with an abnormal flow reserve, CFR in patients with left ventricular hyper trophy was reduced due to higher baseline flow velocities (27+/-11 vs. 20 /- 6 cm/sec, P=0.004). Furthermore, resting flow velocity increased as a fu nction of donor age (r=0.264, P=0.047), while hyperemic flow velocity was n ot different, Other patient characteristics and hemodynamics did not affect CFR. Conclusion. The presence of left ventricular hypertrophy and higher donor a ges independently contribute to a reduced CFR in patients after heart trans plantation. This reduction in CFR is due to elevated baseline flow velociti es rather than to a change in hyperemic flow velocities. These findings sho uld be taken into account for the interpretation of reduced CFR values obta ined by intracoronary Doppler in heart transplant recipients without angiog raphically overt coronary lesions.