Ratio of Pulmonary Artery Diameter to Ascending Aortic Diameter as a Predictive Tool for Severe Primary Graft Dysfunction in Heart Transplants

Abstract

The Ratio of pulmonary artery diameter to ascending aortic diameter (PA:Ao ratio) on computed tomography (CT) is a recent predictive tool known to be associated with severity of heart failure and right heart failure after left ventricular assist device implantation. We searched for a predictive use of PA:Ao ratio in heart transplanted patients METHODS: We collected extensive data from heart transplanted patients in our institution from 2012 to 2018. The diameters of the ascending aorta and the pulmonary artery were defined as the diameter at the level of the artery pulmonary bifurcation in a transaxial slice. Patients were separated into two groups: those with a PA:Ao ratio <1 and those with a PA:Ao ratio >1. We compared the incidence of severe primary graft dysfunction and early ICU death between these two groups. Secondary endpoint was the rate of high pulmonary vascular resistance in both groups. Between 2012 and 2018, 144 consecutive patients were heart transplanted. 50 had a PA:Ao ratio >1 (34,7%) and 94 had a PA:Ao ratio <1 (65,2%). Incidence of severe primary graft dysfunction was significantly higher in patients who had larger pulmonary arteries (48% Vs 15,9% p< 0,0001), mortality in ICU however did not differ (16% Vs 13,8%, p=0,919). Pulmonary vascular resistance superior to 2 woods was significantly associated with PA:Ao Ratio >1 compared to PA:Ao Ratio <1 (54% Vs 37,2 % p=0,047) but was less predictive for severe PGD (38,6% Vs 48% p=0, 246). PA:Ao ratio is a robust tool for prediction of severe primary graft failure in heart transplantation. Further studies should explore our findings for external validation.