PET-CT Defined Micro-Vascular Dysfunction and Cardiac Allograft Vasculopathy Risk Factors in Heart Transplant Recipients

PurposeMicrovascular dysfunction (MVD) is considered a form of cardiac allograft vasculopathy (CAV) and independently associated with poor prognosis after heart transplant (HT). It is unknown whether traditional risk factors for CAV are also applicable to MVD. Therefore, in this study, we analyzed factors associated with MVD in patients without epicardial CAV.MethodsThis was a single center retrospective analysis of all HT recipients who completed a PET scan within one year after a normal baseline left heart catheterization (LHC) excluding epicardial CAV. Abnormal PET indices indicating MVD, were defined as any of: myocardial flow reserve (MFR) < 2.9, stress blood flow (SBF) < 2.3, or coronary vascular resistance (CVR) > 55. We compared demographic, metabolic (e.g. diabetes mellitus (DM), hypertension) and traditional (e.g. sex mismatch, treated rejection) risk factors for CAV, between patients with and without MVD.ResultsWe included 99 patients at a mean age of 52±14, 67 (68%) were males. MVD was found in 52 patients (53%). We did not find any donor risk factors significantly associated with recipient MVD, Table. Recipients risk factors for MVD included - DM (26 (50%) vs. 14 (30%), p=0.041) and hypertension (40 (77%) vs. 24 (51%), p=0.041) in patients with and without MVD, respectively. In a multivariate binary logistic regression model, adjusted for donor and recipient age, DM, hypertension, as well as ischemic time, sex mismatch, CMV high risk status and prior episodes of treated rejection, recipient hypertension was the only significant determinant of MVD development (OR=4.99, 95%CI [1.28-19.42], p=0.020).ConclusionIn this study, MVD was more associated with metabolic risk determinants rather than traditional CAV risk factors. This suggests two distinct phenotypes of CAV with potentially different therapeutic implications. These concepts warrant further investigation. Microvascular dysfunction (MVD) is considered a form of cardiac allograft vasculopathy (CAV) and independently associated with poor prognosis after heart transplant (HT). It is unknown whether traditional risk factors for CAV are also applicable to MVD. Therefore, in this study, we analyzed factors associated with MVD in patients without epicardial CAV. This was a single center retrospective analysis of all HT recipients who completed a PET scan within one year after a normal baseline left heart catheterization (LHC) excluding epicardial CAV. Abnormal PET indices indicating MVD, were defined as any of: myocardial flow reserve (MFR) < 2.9, stress blood flow (SBF) < 2.3, or coronary vascular resistance (CVR) > 55. We compared demographic, metabolic (e.g. diabetes mellitus (DM), hypertension) and traditional (e.g. sex mismatch, treated rejection) risk factors for CAV, between patients with and without MVD. We included 99 patients at a mean age of 52±14, 67 (68%) were males. MVD was found in 52 patients (53%). We did not find any donor risk factors significantly associated with recipient MVD, Table. Recipients risk factors for MVD included - DM (26 (50%) vs. 14 (30%), p=0.041) and hypertension (40 (77%) vs. 24 (51%), p=0.041) in patients with and without MVD, respectively. In a multivariate binary logistic regression model, adjusted for donor and recipient age, DM, hypertension, as well as ischemic time, sex mismatch, CMV high risk status and prior episodes of treated rejection, recipient hypertension was the only significant determinant of MVD development (OR=4.99, 95%CI [1.28-19.42], p=0.020). In this study, MVD was more associated with metabolic risk determinants rather than traditional CAV risk factors. This suggests two distinct phenotypes of CAV with potentially different therapeutic implications. These concepts warrant further investigation.