Abstract 1821: Clinical and Functional Determinants of Coronary Flow Reserve in Heart Transplantation: A Contrast-Enhanced Echocardiographic Study
Determination of coronary flow reserve (CFR) is increasingly used to assess the functional significance of cardiac allograft vasculopathy (CAV). Aim of this study was to evaluate determinants of CFR in heart transplantation (HT).
Methods: CFR was measured in the left anterior descending coronary artery by contrast-enhanced transthoracic echocardiography (CE-TTE) in 73 HT recipients (59 male, aged 50±12 years at HT, at 8 ± 4.5 years after HT). CFR was calculated as the ratio of hyperemic (adenosine infusion at a rate of 0.14 mg/kg per min for 5 min) to basal diastolic flow velocity. CFR was measured blindly from angiography and within 24 hours from catheterization. Rejection scores (RS) on endomyocardial biopsy were calculated (International Society for Heart and Lung Transplantation grades: 0=0; 1A=1; 1B=2; 2=3; 3A=4; 3B=5; 4=6) in the first year and in whole follow-up. RS including only severe grades(= or >3A) were also calculated. CAV onset was defined as any lesion > or = 10%. The coronary tree was divided into 17 traits and a CAV severity/diffusion index (SDI) was calculated for each patient summing up the scores assigned to all lesions (10% stenosis=1; 20%=2; 30%=3; 40%=4; 50%=5; 60%=6; 70%=7; 80%=8; 90%=9; 100%=10).
Results: At univariate analysis CFR was related to CAV (p<0.0001), male recipient gender (p=0.01), ejection fraction (p=0.009), haemoglobin (p=0.003), therapy with pred-nisone (p=0.008), interventricular septum thickness (p=0.006), SDI and SDI/traits number (p<0.0001 and p<0.0001, respectively), number of diseased traits (p<0.0001), and ticlopidine therapy (p= 0.03). At stepwise logistic regression analysis CFR was related to CAV presence (β 0.439, p= 0.001), ticlopidine therapy (β −0.212, p= 0.01), interventricular septum thickness (β0.233, p= 0.009), SDI and SDI/traits number (β −0.690, p<0.0001 and β −0.559, p=0.008, respectively).
Conclusions: The presence of left ventricular hypertrophy, CAV and, above all, its severity/diffusion independently contribute to a reduced CFR in patients after HT. This microvascular dysfunction may contribute to the late morbidity and mortality seen in cardiac transplant patients with coronary occlusive disease.